/* Layout: course rail on the left, one reading column (~68ch) on the right; the rail folds behind a top bar on phones. */
:root {
  --paper: #f6f7f9;
  --panel: #ffffff;
  --ink: #18202b;
  --soft-ink: #3a4553;
  --muted: #667283;
  --line: #e1e5eb;
  --accent: #2c4fd6;
  --accent-soft: #e9eefd;
  --code-bg: #eef1f5;
  --amber: #96590a;
  --amber-soft: #fbf1df;
  --good: #1d8a5a;
  --font-display: "Geist", "Inter var", "Segoe UI", system-ui, -apple-system, sans-serif;
  --font-serif: "Source Serif 4", Georgia, "Times New Roman", serif;
  --font-mono: "JetBrains Mono", ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  --font-read: var(--font-display);
  --read-size: 17.5px;
  --rail: 292px;
  --sticky-top: env(safe-area-inset-top, 0px);
  --ease: cubic-bezier(.23, 1, .32, 1);
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #0d1117; --panel: #131922; --ink: #e4e8ee; --soft-ink: #c3cad4; --muted: #8e99a8; --line: #232c39;
    --accent: #93a9ff; --accent-soft: #1a2442; --code-bg: #1a212c; --amber: #f0b45b; --amber-soft: #2c2213; --good: #6fd6a8;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --paper: #0d1117; --panel: #131922; --ink: #e4e8ee; --soft-ink: #c3cad4; --muted: #8e99a8; --line: #232c39;
  --accent: #93a9ff; --accent-soft: #1a2442; --code-bg: #1a212c; --amber: #f0b45b; --amber-soft: #2c2213; --good: #6fd6a8;
  color-scheme: dark;
}
:root[data-read="serif"] { --font-read: var(--font-serif); }
:root[data-size="s"] { --read-size: 16px; }
:root[data-size="l"] { --read-size: 19.5px; }

* { box-sizing: border-box; }
body { margin: 0; background: var(--paper); color: var(--ink); font-family: var(--font-display); font-size: 16px; line-height: 1.6; -webkit-font-smoothing: antialiased; }
a { color: var(--accent); text-underline-offset: 3px; }
a:focus-visible, button:focus-visible, summary:focus-visible, input:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; border-radius: 4px; }
body::before { content: ""; position: fixed; inset: 0 0 auto; height: env(safe-area-inset-top, 0px); z-index: 10; background: var(--panel); }
kbd { display: inline-grid; place-items: center; min-width: 20px; height: 20px; padding: 0 5px; font: 500 11px/1 var(--font-mono); color: var(--muted); background: var(--panel); border: 1px solid var(--line); border-bottom-width: 2px; border-radius: 5px; }
.icon { width: 16px; height: 16px; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; flex: none; }

/* Top bar (phones) */
.topbar {
  position: sticky; top: env(safe-area-inset-top, 0px); z-index: 6;
  display: none; align-items: center; gap: 8px; padding-block: 10px;
  padding-left: max(16px, env(safe-area-inset-left, 0px)); padding-right: max(16px, env(safe-area-inset-right, 0px));
  background: color-mix(in srgb, var(--panel) 88%, transparent); backdrop-filter: blur(10px); border-bottom: 1px solid var(--line);
}
.topbar .brand { margin-right: auto; }
.brand { display: inline-flex; align-items: center; gap: 9px; font-weight: 600; font-size: 16.5px; color: var(--ink); text-decoration: none; letter-spacing: -0.01em; }
.brand-mark { width: 22px; height: 22px; flex: none; display: block; }
.brand-mark rect { fill: var(--ink); }
.brand-mark rect:last-child { fill: var(--accent); }
.tb-btn { display: inline-flex; align-items: center; gap: 6px; font: 500 13px/1 var(--font-display); color: var(--ink); background: var(--paper); border: 1px solid var(--line); border-radius: 8px; padding: 8px 10px; cursor: pointer; }

.shell { display: grid; grid-template-columns: var(--rail) minmax(0, 1fr); min-height: 100vh; }

/* Rail */
.rail {
  position: sticky; top: 0; align-self: start; height: 100vh; overflow-y: auto; overscroll-behavior: contain;
  display: flex; flex-direction: column; gap: 4px;
  background: var(--panel); border-right: 1px solid var(--line);
  padding: 22px 16px 24px; padding-left: max(16px, env(safe-area-inset-left, 0px));
  font-size: 14px; line-height: 1.35;
}
.rail-top { position: relative; padding: 0 8px 14px; }
.rail-hide { position: absolute; right: 0; top: 0; width: 28px; height: 28px; border-radius: 7px; border: 1px solid var(--line); background: var(--paper); color: var(--muted); font-size: 15px; line-height: 1; cursor: pointer; }
.rail-hide:hover, .rail-show:hover { color: var(--accent); border-color: color-mix(in srgb, var(--accent) 50%, var(--line)); }
.rail-show { display: none; position: fixed; z-index: 7; top: calc(14px + env(safe-area-inset-top, 0px)); left: max(14px, env(safe-area-inset-left, 0px)); width: 34px; height: 34px; border-radius: 9px; border: 1px solid var(--line); background: var(--panel); color: var(--ink); font-size: 16px; line-height: 1; cursor: pointer; box-shadow: 0 6px 18px -8px rgba(0, 0, 0, .3); }
.shell.rail-hidden { grid-template-columns: minmax(0, 1fr); }
.shell.rail-hidden .rail { display: none; }
body.rail-collapsed .rail-show { display: block; }
.rail-sub { color: var(--muted); font-size: 12.5px; margin: 6px 0 0 31px; text-wrap: balance; }
.search-btn { display: flex; align-items: center; gap: 8px; width: 100%; margin: 4px 0 10px; padding: 8px 10px; border: 1px solid var(--line); border-radius: 9px; background: var(--paper); color: var(--muted); font: 400 13.5px/1 var(--font-display); cursor: pointer; transition: border-color .2s, color .2s; }
.search-btn:hover { border-color: color-mix(in srgb, var(--accent) 50%, var(--line)); color: var(--ink); }
.search-btn kbd { margin-left: auto; }
.rail-home { display: flex; align-items: center; gap: 8px; color: var(--ink); text-decoration: none; padding: 7px 10px; border-radius: 7px; margin-bottom: 10px; }
.rail-home:hover { background: var(--paper); }
.rail-home.is-active { background: var(--accent-soft); color: var(--accent); }
.nav-part { margin-bottom: 14px; }
.nav-part-title { margin: 0 0 4px; padding: 0 10px; font-weight: 500; font-size: 13px; color: var(--ink); }
.part-num { display: block; font: 500 10.5px/1.4 var(--font-mono); letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); }
.nav-part ol { list-style: none; margin: 0; padding: 0; display: grid; gap: 1px; }
.nav-part li > a, .nav-part li.later { display: grid; grid-template-columns: 28px minmax(0, 1fr) auto 16px; gap: 6px; align-items: center; padding: 6px 10px; border-radius: 7px; }
.nav-part li.later { grid-template-columns: 28px minmax(0, 1fr); }
.nav-part li > a { color: var(--soft-ink); text-decoration: none; transition: background .15s, color .15s; }
.nav-part li > a:hover { background: var(--paper); color: var(--ink); }
.nav-part li > a.is-active { background: var(--accent-soft); color: var(--accent); }
.nav-part li.later { color: var(--muted); opacity: 0.6; }
.lid { font: 400 11.5px/1 var(--font-mono); color: var(--muted); font-variant-numeric: tabular-nums; }
a.is-active .lid { color: var(--accent); }
.prog { width: 16px; height: 16px; }
.prog svg { display: block; width: 16px; height: 16px; }
.prog .ring-bg { fill: none; stroke: var(--line); stroke-width: 2.4; }
.prog .ring { fill: none; stroke: var(--accent); stroke-width: 2.4; stroke-linecap: round; transform: rotate(-90deg); transform-origin: center; transition: stroke-dashoffset .6s var(--ease); }
.prog .done-bg { fill: var(--good); }
.prog .done-ck { fill: none; stroke: var(--panel); stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }
.rail-foot { margin-top: auto; padding: 14px 8px 0; display: flex; gap: 8px; align-items: center; color: var(--muted); font-size: 12.5px; }
.rail-foot .tb-btn { margin-left: auto; }

.chip { display: inline-block; font: 500 10px/1 var(--font-mono); letter-spacing: 0.06em; text-transform: uppercase; padding: 4px 6px; border-radius: 4px; background: var(--accent-soft); color: var(--accent); vertical-align: middle; white-space: nowrap; }
.chip.draft { background: var(--amber-soft); color: var(--amber); }

/* Main */
main { min-width: 0; padding-block: 56px 110px; padding-left: max(16px, env(safe-area-inset-left, 0px)); padding-right: max(16px, env(safe-area-inset-right, 0px)); }

/* Home */
.home { max-width: 1020px; margin: 0 auto; }
.hero { position: relative; display: grid; grid-template-columns: minmax(0, 1.05fr) minmax(0, 1fr); gap: 40px; align-items: center; margin-bottom: 44px; }
.hero::before { content: ""; position: absolute; inset: -60px -40px -30px; z-index: -1; background-image: radial-gradient(color-mix(in srgb, var(--muted) 35%, transparent) 1px, transparent 1.2px); background-size: 22px 22px; -webkit-mask-image: radial-gradient(70% 70% at 40% 40%, #000 30%, transparent 75%); mask-image: radial-gradient(70% 70% at 40% 40%, #000 30%, transparent 75%); opacity: .55; }
.hero h1 { font-weight: 600; font-size: clamp(40px, 6vw, 60px); line-height: 1.02; letter-spacing: -0.04em; margin: 0 0 18px; text-wrap: balance; }
.hero h1 em { font-style: normal; color: var(--accent); }
.hero .lede { font-size: 18.5px; line-height: 1.55; color: var(--soft-ink); margin: 0 0 26px; max-width: 32em; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 14px; align-items: center; }
.btn { display: inline-flex; align-items: center; gap: 8px; font: 500 15px/1 var(--font-display); text-decoration: none; padding: 12px 16px; border-radius: 9px; background: var(--ink); color: var(--paper); }
.btn .icon { transition: transform .25s var(--ease); }
.btn-ghost { background: transparent; color: var(--ink); border: 1px solid var(--line); }
.btn:hover .icon { transform: translateX(3px); }
.hero-note { font-size: 13.5px; color: var(--muted); display: inline-flex; align-items: center; gap: 8px; }
.hero-note::before { content: ""; width: 7px; height: 7px; border-radius: 50%; background: var(--good); box-shadow: 0 0 0 3px color-mix(in srgb, var(--good) 22%, transparent); }

.term { background: #0d1117; border: 1px solid #252e3b; border-radius: 12px; box-shadow: 0 20px 50px -24px rgba(10, 20, 40, .45); overflow: hidden; font: 13px/1.7 var(--font-mono); color: #c9d1db; }
.term-bar { display: flex; align-items: center; gap: 6px; padding: 10px 12px; border-bottom: 1px solid #1f2733; }
.term-bar i { width: 10px; height: 10px; border-radius: 50%; background: #2a3341; }
.term-bar span { margin-left: 8px; font-size: 11.5px; color: #7d8898; }
.term pre { margin: 0; padding: 14px 16px 16px; min-height: 236px; white-space: pre-wrap; font: inherit; }
.term .p { color: #6fd6a8; } .term .d { color: #7d8898; } .term .v { color: #f3c06b; } .term .h { color: #ff8a6b; }
.cursor { display: inline-block; width: 7px; height: 15px; background: #c9d1db; vertical-align: -2px; }

.tracks { list-style: none; margin: 0 0 44px; padding: 0; display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 12px; }
.track { position: relative; height: 100%; display: flex; flex-direction: column; gap: 6px; padding: 18px 18px 16px; border: 1px solid var(--line); border-radius: 14px; background: var(--panel); color: var(--ink); text-decoration: none; transition: border-color .2s, box-shadow .2s; }
a.track:hover { border-color: color-mix(in srgb, var(--accent) 50%, var(--line)); box-shadow: 0 12px 30px -20px color-mix(in srgb, var(--accent) 70%, transparent); }
.track.is-soon { background: transparent; border-style: dashed; }
.track.is-soon .track-ico, .track.is-soon h2 { opacity: .7; }
.track-ico { display: grid; place-items: center; width: 34px; height: 34px; margin-bottom: 6px; border-radius: 9px; background: var(--accent-soft); color: var(--accent); }
.track.is-soon .track-ico { background: var(--code-bg); color: var(--muted); }
.track-ico .icon { width: 18px; height: 18px; }
.track-k { font: 500 11px/1.4 var(--font-mono); letter-spacing: .07em; text-transform: uppercase; color: var(--muted); }
.track h2 { margin: 0; font-size: 16.5px; font-weight: 600; line-height: 1.3; letter-spacing: -0.015em; text-wrap: balance; }
.track p { margin: 0; font-size: 14px; line-height: 1.55; color: var(--muted); }
.track-go { margin-top: auto; padding-top: 8px; font-size: 13.5px; font-weight: 500; color: var(--accent); }
.rail-new { margin-left: auto; font: 500 9.5px/1 var(--font-mono); letter-spacing: .06em; text-transform: uppercase; padding: 3px 5px; border-radius: 4px; background: var(--accent-soft); color: var(--accent); }
@media (max-width: 1100px) { .tracks { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 560px) { .tracks { grid-template-columns: minmax(0, 1fr); } }
@media (prefers-reduced-motion: no-preference) { a.track { transition: border-color .2s, box-shadow .2s, scale .15s var(--ease); } a.track:active { scale: .985; } }
.home-road { margin: 0 0 52px; }
.how { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 14px; margin-bottom: 60px; }
.how > div { padding: 18px 18px 20px; border: 1px solid var(--line); border-radius: 12px; background: var(--panel); transition: border-color .25s, transform .3s var(--ease); }
.how > div:hover { border-color: color-mix(in srgb, var(--accent) 45%, var(--line)); }
.how .icon { width: 20px; height: 20px; color: var(--accent); margin-bottom: 12px; }
.how h2 { font-size: 15.5px; font-weight: 600; margin: 0 0 6px; letter-spacing: -0.01em; }
.how p { margin: 0; font-size: 14.5px; line-height: 1.55; color: var(--muted); }

.map-title { margin: 0 0 16px; font-size: 22px; font-weight: 600; letter-spacing: -0.02em; }
.map { list-style: none; padding: 0; margin: 0; display: grid; border-top: 1px solid var(--line); }
.map-part { display: grid; grid-template-columns: 260px minmax(0, 1fr); gap: 24px; padding: 22px 0; border-bottom: 1px solid var(--line); scroll-margin-top: 90px; }
.map-head h3 { font-size: 17px; font-weight: 600; line-height: 1.3; margin: 4px 0 6px; letter-spacing: -0.01em; text-wrap: balance; }
.map-scale { font: 500 11.5px/1 var(--font-mono); color: var(--muted); }
.map-part.is-open .map-scale { color: var(--accent); }
.map-stage { margin: 0; font-size: 13px; color: var(--muted); }
.map-lessons { list-style: none; margin: 0; padding: 0; display: grid; gap: 7px; font-size: 15px; line-height: 1.35; }
.map-lessons .lid { display: inline-block; width: 34px; }
.map-lessons a { text-decoration: none; color: var(--ink); background: linear-gradient(currentColor, currentColor) 0 100% / 0 1px no-repeat; transition: background-size .3s var(--ease), color .2s; }
.map-lessons a:hover { color: var(--accent); background-size: 100% 1px; }
.map-lessons .later { color: var(--muted); opacity: 0.7; }
.draft-note { margin: 36px 0 0; font-size: 13.5px; color: var(--muted); }

/* Lesson */
.lesson { max-width: 720px; margin: 0 auto; }
.page-doc { max-width: 720px; margin: 0 auto; padding-bottom: 40px; }
.page-doc-head h1 { font-weight: 600; font-size: clamp(30px, 4.6vw, 42px); line-height: 1.1; letter-spacing: -0.035em; margin: 0 0 14px; text-wrap: balance; }
.page-doc-lede { font-size: 18px; line-height: 1.6; color: var(--soft-ink); margin: 0 0 8px; }
.page-doc .prose a, .home-foot a, .rail-links a { color: var(--accent); }
.nf-list { list-style: none; margin: 28px 0 0; padding: 0; display: grid; gap: 10px; }
.nf-list a { display: flex; flex-direction: column; gap: 2px; padding: 14px 16px; border: 1px solid var(--line); border-radius: 10px; background: var(--panel); text-decoration: none; color: var(--ink); }
.nf-list a:hover { border-color: var(--accent); }
.nf-list span { font-size: 14px; color: var(--muted); }
.home-foot { display: flex; flex-wrap: wrap; gap: 8px 18px; margin: 48px 0 8px; padding-top: 18px; border-top: 1px solid var(--line); font-size: 13.5px; color: var(--muted); }
.home-foot span { margin-right: auto; }
.rail-links { display: flex; gap: 14px; padding: 12px 8px 0; font-size: 12.5px; }
.rail-links a { color: var(--muted); text-decoration: none; }
.rail-links a:hover { color: var(--accent); }
.eyebrow { font: 500 11.5px/1.4 var(--font-mono); letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); margin: 0 0 12px; }
.lesson-head h1 { font-weight: 600; font-size: clamp(30px, 4.6vw, 42px); line-height: 1.1; letter-spacing: -0.035em; margin: 0 0 14px; text-wrap: balance; }
.lesson-meta { display: flex; flex-wrap: wrap; gap: 6px 14px; align-items: center; font-size: 13.5px; color: var(--muted); margin: 0 0 24px; }
.lesson-meta > span + span::before { content: "·"; margin-right: 14px; color: var(--line); }
.lesson-meta > .chip::before { display: none; }
.where { font-family: var(--font-serif); font-size: 17px; line-height: 1.6; color: var(--soft-ink); border-left: 2px solid var(--accent); padding: 2px 0 2px 16px; margin: 0 0 24px; font-style: italic; }
.learn { margin: 0 0 22px; padding: 16px 18px; background: var(--panel); border: 1px solid var(--line); border-radius: 12px; }
.learn-title { margin: 0 0 12px; font: 500 11px/1.3 var(--font-mono); letter-spacing: .1em; text-transform: uppercase; color: var(--muted); }
.learn ul { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px 24px; }
.learn li { display: grid; grid-template-columns: 18px minmax(0, 1fr); gap: 10px; align-items: start; font-size: 14.5px; line-height: 1.45; color: var(--soft-ink); }
.ck { width: 18px; height: 18px; margin-top: 1px; }
.ck rect { fill: var(--accent-soft); stroke: color-mix(in srgb, var(--accent) 55%, transparent); stroke-width: 1.2; }
.ck path { fill: none; stroke: var(--accent); stroke-width: 1.9; stroke-linecap: round; stroke-linejoin: round; }
.resume { display: flex; align-items: center; justify-content: space-between; gap: 12px; width: 100%; margin: 0 0 22px; padding: 12px 16px; border: 1px solid color-mix(in srgb, var(--accent) 45%, var(--line)); border-radius: 10px; background: var(--accent-soft); color: var(--accent); font: 500 14px/1.3 var(--font-display); text-align: left; cursor: pointer; }
.resume span { color: var(--ink); }
.resume[hidden] { display: none; }
.crumb { display: none; margin: 0; font-size: 14.5px; font-weight: 500; color: var(--ink); }
.crumb-id { font: 500 11px/1 var(--font-mono); letter-spacing: .06em; text-transform: uppercase; color: var(--muted); margin-right: 6px; }
.lesson:not(.on-first) .lesson-head, .lesson:not(.on-first):not(.show-trace) .roadmap { display: none; }
.lesson:not(.on-first) .crumb { display: block; }
.lesson:not(.on-last) .pager { display: none; }
.lesson:not(.on-last) .sc-signup-slot { display: none; }

.readbar {
  position: sticky; top: var(--sticky-top); z-index: 4;
  display: flex; align-items: center; gap: 10px; margin: 24px 0 8px; padding-block: 10px;
  background: color-mix(in srgb, var(--paper) 90%, transparent); backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line); font-size: 13px; color: var(--muted);
}
.rb-toggle, .rb-icon { flex: none; display: inline-flex; align-items: center; gap: 6px; font: 500 12.5px/1 var(--font-display); color: var(--ink); background: var(--panel); border: 1px solid var(--line); border-radius: 7px; padding: 7px 9px; cursor: pointer; transition: border-color .2s, color .2s; }
.rb-toggle[aria-expanded="true"], .rb-toggle:hover, .rb-icon:hover { border-color: color-mix(in srgb, var(--accent) 50%, var(--line)); color: var(--accent); }
.rb-segs { display: flex; gap: 3px; flex: 1 1 auto; min-width: 0; }
.rb-seg { flex: 1; box-sizing: content-box; height: 6px; border: 0; padding: 9px 0; margin: -9px 0; border-radius: 3px; background: var(--line); background-clip: content-box; overflow: hidden; cursor: pointer; transition: transform .2s; }
.rb-seg i { border-radius: 3px; }
.rb-seg:hover { transform: scaleY(1.5); }
.rb-seg i { display: block; height: 100%; width: 0; background: var(--accent); transition: width .25s ease; }
.rb-seg.is-current { background: color-mix(in srgb, var(--accent) 20%, var(--line)); }
.rb-label { flex: 0 1 42%; min-width: 0; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; text-align: right; color: var(--soft-ink); }

/* Reading */
.prose { min-width: 0; font-family: var(--font-read); font-size: var(--read-size); line-height: 1.72; color: var(--soft-ink); }
.prose > * + * { margin-top: 1.1em; }
.prose p, .prose ul, .prose ol { margin-bottom: 0; }
.prose strong { font-weight: 600; color: var(--ink); }
.prose h2, .prose h3 { font-family: var(--font-display); color: var(--ink); text-wrap: balance; scroll-margin-top: 80px; }
.prose h2 { font-size: 1.5em; font-weight: 600; line-height: 1.2; letter-spacing: -0.025em; margin: 2.2em 0 0; }
.prose h3 { font-size: 1.15em; font-weight: 600; line-height: 1.3; letter-spacing: -0.015em; margin: 1.9em 0 0; }
.prose h2 + *, .prose h3 + * { margin-top: 0.55em; }
.prose hr { border: 0; border-top: 1px solid var(--line); margin: 2.4em 0; }
.prose ul, .prose ol { padding-left: 1.25em; }
.prose li + li { margin-top: 0.4em; }
.prose li::marker { color: var(--muted); }
.prose a { text-decoration: none; background: linear-gradient(currentColor, currentColor) 0 100% / 100% 1px no-repeat; transition: background-size .3s var(--ease); }
.prose a:hover { background-size: 100% 2px; }
.prose a.xref { background-image: linear-gradient(90deg, currentColor 50%, transparent 0); background-size: 4px 1px; background-repeat: repeat-x; }
.prose blockquote { margin: 1.3em 0 0; padding: 14px 18px; background: var(--accent-soft); border-left: 3px solid var(--accent); border-radius: 0 10px 10px 0; color: var(--ink); }
.prose blockquote p { margin: 0; }
.prose :not(pre) > code { font-family: var(--font-mono); font-size: 0.8em; color: var(--ink); background: var(--code-bg); border: 1px solid var(--line); padding: 0.1em 0.38em; border-radius: 5px; overflow-wrap: anywhere; }
.step-kicker { margin: 0 0 8px !important; font: 500 11px/1.3 var(--font-mono); letter-spacing: .08em; text-transform: uppercase; color: var(--muted); }
.step > h2:first-of-type { margin-top: 0; }
.step.is-story > p:nth-of-type(2) { font-size: 1.16em; line-height: 1.6; color: var(--ink); }
.tally strong { display: inline-flex; align-items: center; gap: 8px; padding: 6px 12px; border-radius: 999px; background: var(--accent-soft); color: var(--accent); font: 500 13px/1.2 var(--font-mono); }
.tally strong::before { content: ""; width: 7px; height: 7px; border-radius: 50%; background: currentColor; }

/* Code */
.code { margin-left: 0; margin-right: 0; background: #0d1117; border: 1px solid #222b37; border-radius: 10px; overflow: hidden; }
.code figcaption { display: flex; align-items: center; justify-content: space-between; gap: 10px; padding: 7px 8px 7px 14px; border-bottom: 1px solid #1d2531; background: #111720; }
.code-lang { font: 500 10.5px/1 var(--font-mono); letter-spacing: .08em; text-transform: uppercase; color: #7d8898; }
.copy { font: 500 11.5px/1 var(--font-display); color: #aab4c1; background: transparent; border: 1px solid #2a3442; border-radius: 6px; padding: 5px 8px; cursor: pointer; transition: color .2s, border-color .2s, background .2s; }
.copy:hover { color: #fff; border-color: #3b4757; }
.copy.done { color: #6fd6a8; border-color: #2f6b52; background: #11261d; }
.code pre { margin: 0; padding: 14px 16px; overflow-x: auto; font: 13.5px/1.65 var(--font-mono); color: #d3dae3; tab-size: 2; }
.tk-k { color: #8ea8ff; } .tk-s { color: #9fe0b8; } .tk-n { color: #f3c06b; } .tk-c { color: #6b7789; font-style: italic; } .tk-a { color: #ff9e7d; } .tk-f { color: #c9a7ff; }

/* Tables */
.table-wrap { overflow-x: auto; border: 1px solid var(--line); border-radius: 10px; background: var(--panel); }
.table-wrap table { border-collapse: collapse; width: 100%; font-family: var(--font-display); font-size: 14.5px; line-height: 1.45; color: var(--ink); }
.table-wrap th, .table-wrap td { text-align: left; padding: 9px 14px; border-bottom: 1px solid var(--line); vertical-align: top; }
.table-wrap th { font-weight: 500; font-size: 12.5px; color: var(--muted); background: var(--paper); }
.table-wrap tr:last-child td { border-bottom: 0; }
.table-wrap tbody tr { transition: background .15s; }
.table-wrap tbody tr:hover { background: color-mix(in srgb, var(--accent-soft) 60%, transparent); }
.table-wrap td { font-variant-numeric: tabular-nums; }

/* Exercises */
.prose details { border: 1px solid var(--line); border-radius: 10px; background: var(--panel); padding: 0; overflow: hidden; transition: border-color .2s; }
.prose details + details { margin-top: 10px; }
.prose details[open] { border-color: color-mix(in srgb, var(--accent) 45%, var(--line)); }
.prose details summary { list-style: none; display: block; position: relative; padding: 14px 128px 14px 16px; cursor: pointer; font-family: var(--font-display); font-size: 15.5px; line-height: 1.55; color: var(--ink); }
.prose details summary::-webkit-details-marker { display: none; }
.prose details summary::after { content: "Show answer"; position: absolute; top: 14px; right: 14px; font: 500 11px/1 var(--font-mono); letter-spacing: .04em; color: var(--accent); background: var(--accent-soft); border-radius: 999px; padding: 6px 9px; white-space: nowrap; }
.prose details[open] summary::after { content: "Hide"; }
.prose details summary b { color: var(--accent); font-weight: 600; margin-right: 4px; }
.prose details > p { margin: 0; padding: 0 16px 16px; font-size: 0.95em; color: var(--soft-ink); }
.prose details > p::before { content: ""; display: block; border-top: 1px dashed var(--line); margin-bottom: 12px; }

/* Step navigation */
.step-nav { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 52px; }
.step-btn { display: flex; flex-direction: column; gap: 5px; padding: 15px 18px; border-radius: 12px; border: 1px solid var(--line); background: var(--panel); color: var(--ink); text-align: left; cursor: pointer; font-family: var(--font-display); transition: border-color .2s, transform .3s var(--ease), box-shadow .3s; }
.step-btn.next { grid-column: 2; text-align: right; align-items: flex-end; background: var(--ink); border-color: var(--ink); color: var(--paper); }
.step-btn:hover { border-color: var(--accent); }
.step-btn.next:hover { box-shadow: 0 12px 28px -14px color-mix(in srgb, var(--ink) 60%, transparent); }
.step-dir { display: inline-flex; align-items: center; gap: 6px; font: 500 10.5px/1.3 var(--font-mono); letter-spacing: .06em; text-transform: uppercase; opacity: .7; }
.step-title { font-size: 16px; font-weight: 500; line-height: 1.3; }
.step-done { grid-column: 2; margin: 0; align-self: center; text-align: right; color: var(--muted); font-size: 14px; }
.kbd-hint { grid-column: 1 / -1; margin: 6px 0 0; display: flex; flex-wrap: wrap; gap: 6px 14px; justify-content: center; font-size: 12.5px; color: var(--muted); }
.kbd-hint span { display: inline-flex; align-items: center; gap: 5px; }
@media (hover: none) { .kbd-hint { display: none; } }

.pager { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 28px; padding-top: 24px; border-top: 1px solid var(--line); }
.pager-link { display: flex; flex-direction: column; gap: 4px; padding: 14px 16px; border: 1px solid var(--line); border-radius: 10px; text-decoration: none; color: var(--ink); background: var(--panel); transition: border-color .2s, transform .3s var(--ease); }
.pager-link:hover { border-color: var(--accent); }
.pager-link.next { text-align: right; }
.pager-link.is-end { background: transparent; border-style: dashed; }
.pager-dir { font: 500 10.5px/1.3 var(--font-mono); letter-spacing: 0.06em; text-transform: uppercase; color: var(--muted); }
.pager-title { font-weight: 500; font-size: 15.5px; line-height: 1.3; }
.pager-note { font-size: 13px; color: var(--muted); }

/* Command palette */
.palette { position: fixed; inset: 0; z-index: 30; display: grid; place-items: start center; padding: 12vh 16px 16px; background: color-mix(in srgb, #0a0f16 45%, transparent); backdrop-filter: blur(3px); }
.palette[hidden] { display: none; }
.pal-box { width: min(620px, 100%); background: var(--panel); border: 1px solid var(--line); border-radius: 14px; box-shadow: 0 30px 80px -20px rgba(5, 10, 20, .5); overflow: hidden; }
.pal-in { display: flex; align-items: center; gap: 10px; padding: 14px 16px; border-bottom: 1px solid var(--line); color: var(--muted); }
.pal-in input { flex: 1; min-width: 0; border: 0; outline: 0; background: transparent; color: var(--ink); font: 400 16px/1.3 var(--font-display); }
.pal-list { list-style: none; margin: 0; padding: 6px; max-height: min(420px, 55vh); overflow-y: auto; }
.pal-item { display: grid; grid-template-columns: 44px minmax(0, 1fr) auto; gap: 10px; align-items: center; padding: 9px 10px; border-radius: 8px; cursor: pointer; font-size: 14.5px; color: var(--ink); }
.pal-item .lid { font-size: 11px; }
.pal-item small { display: block; color: var(--muted); font-size: 12.5px; margin-top: 2px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.pal-item mark { background: color-mix(in srgb, var(--accent) 22%, transparent); color: inherit; border-radius: 3px; }
.pal-item.on { background: var(--accent-soft); }
.pal-item.on .pal-go { opacity: 1; }
.pal-go { opacity: 0; color: var(--accent); font: 500 11px/1 var(--font-mono); }
.pal-empty { padding: 22px; text-align: center; color: var(--muted); font-size: 14px; }
.pal-foot { display: flex; gap: 14px; padding: 9px 14px; border-top: 1px solid var(--line); font-size: 12px; color: var(--muted); background: var(--paper); }
.pal-foot span { display: inline-flex; align-items: center; gap: 5px; }

/* Settings */
.settings { position: fixed; z-index: 25; right: max(16px, env(safe-area-inset-right, 0px)); bottom: calc(16px + env(safe-area-inset-bottom, 0px)); width: 280px; padding: 14px; background: var(--panel); border: 1px solid var(--line); border-radius: 14px; box-shadow: 0 24px 60px -24px rgba(5, 10, 20, .45); display: grid; gap: 12px; }
.settings[hidden] { display: none; }
.set-head { display: flex; justify-content: space-between; align-items: center; font-weight: 500; font-size: 14px; }
.set-close { border: 0; background: none; color: var(--muted); cursor: pointer; font-size: 18px; line-height: 1; padding: 2px 4px; }
.set-row { display: grid; gap: 6px; }
.set-row > span { font: 500 10.5px/1 var(--font-mono); letter-spacing: .08em; text-transform: uppercase; color: var(--muted); }
.set-seg { display: grid; grid-auto-flow: column; grid-auto-columns: 1fr; gap: 3px; padding: 3px; background: var(--paper); border: 1px solid var(--line); border-radius: 9px; }
.set-seg button { border: 0; background: transparent; color: var(--muted); font: 500 13px/1 var(--font-display); padding: 8px 6px; border-radius: 6px; cursor: pointer; transition: background .2s, color .2s; }
.set-seg button[aria-pressed="true"] { background: var(--panel); color: var(--ink); box-shadow: 0 1px 2px rgba(0, 0, 0, .08), inset 0 0 0 1px var(--line); }

/* Toast */
.toast { position: fixed; z-index: 28; left: 50%; bottom: calc(22px + env(safe-area-inset-bottom, 0px)); transform: translateX(-50%); display: flex; align-items: center; gap: 10px; padding: 11px 16px; background: var(--ink); color: var(--paper); border-radius: 999px; font-size: 14px; box-shadow: 0 16px 40px -16px rgba(5, 10, 20, .6); }
.toast[hidden] { display: none; }
.toast svg { width: 18px; height: 18px; fill: none; stroke: #6fd6a8; stroke-width: 2.2; stroke-linecap: round; stroke-linejoin: round; }

@media (prefers-reduced-motion: no-preference) {
  html { scroll-behavior: smooth; }
  [data-view]:not([hidden]) { animation: viewIn .3s var(--ease) both; }
  .step.enter-next { animation: fromRight .26s var(--ease) both; }
  .step.enter-prev { animation: fromLeft .26s var(--ease) both; }
  @keyframes viewIn { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: none; } }
  @keyframes fromRight { from { opacity: 0; transform: translateX(12px); filter: blur(3px); } to { opacity: 1; transform: none; filter: none; } }
  @keyframes fromLeft { from { opacity: 0; transform: translateX(-12px); filter: blur(3px); } to { opacity: 1; transform: none; filter: none; } }
  .hero > div > * { animation: rise .8s var(--ease) both; }
  .hero > div > :nth-child(2) { animation-delay: .07s; }
  .hero > div > :nth-child(3) { animation-delay: .14s; }
  .hero .term { animation: rise .9s var(--ease) .2s both; }
  .rise { animation: rise .7s var(--ease) both; }
  @keyframes rise { from { opacity: 0; transform: translateY(16px); } to { opacity: 1; transform: none; } }
  .cursor { animation: blinkc 1.1s steps(1) infinite; }
  @keyframes blinkc { 50% { opacity: 0; } }
  /* Press feedback: anything you click gives a little under the finger. */
  .btn { transition: scale .15s var(--ease); }
  .search-btn, .rb-toggle, .rb-icon { transition: border-color .2s, color .2s, scale .15s var(--ease); }
  .copy { transition: color .2s, border-color .2s, background .2s, scale .15s var(--ease); }
  .step-btn { transition: border-color .2s, box-shadow .3s, scale .15s var(--ease); }
  .pager-link { transition: border-color .2s, scale .15s var(--ease); }
  .set-seg button { transition: background .2s, color .2s, scale .15s var(--ease); }
  .btn:active, .search-btn:active, .rb-toggle:active, .rb-icon:active, .copy:active, .set-seg button:active, .rail-hide:active, .rail-show:active { scale: .96; }
  .step-btn:active, .pager-link:active { scale: .985; }
  .prose details[open] > p { animation: reveal .35s var(--ease) both; }
  @keyframes reveal { from { opacity: 0; transform: translateY(-6px); } to { opacity: 1; transform: none; } }
  .settings:not([hidden]) { animation: pop .18s var(--ease) both; }
  @keyframes fade { from { opacity: 0; } }
  @keyframes pop { from { opacity: 0; transform: translateY(8px) scale(.98); } to { opacity: 1; transform: none; } }
  .toast:not([hidden]) { animation: toastIn .4s var(--ease) both; }
  @keyframes toastIn { from { opacity: 0; transform: translate(-50%, 14px); } to { opacity: 1; transform: translate(-50%, 0); } }
  .toast path { stroke-dasharray: 20; stroke-dashoffset: 20; animation: tick .5s .15s ease forwards; }
  @keyframes tick { to { stroke-dashoffset: 0; } }
  .learn li { animation: rise .6s var(--ease) both; }
  .learn li:nth-child(2) { animation-delay: .06s; } .learn li:nth-child(3) { animation-delay: .12s; } .learn li:nth-child(4) { animation-delay: .18s; }
}

@media (max-width: 960px) {
  .hero { grid-template-columns: minmax(0, 1fr); gap: 28px; }
}
@media (max-width: 900px) {
  :root { --sticky-top: calc(env(safe-area-inset-top, 0px) + 55px); }
  .topbar { display: flex; }
  .shell { grid-template-columns: minmax(0, 1fr); }
  .rail { position: static; height: auto; border-right: 0; border-bottom: 1px solid var(--line); padding-left: max(16px, env(safe-area-inset-left, 0px)); padding-right: max(16px, env(safe-area-inset-right, 0px)); }
  .rail .rail-top, .rail .search-btn { display: none; }
  body.rail-collapsed .rail-show { display: none; }
  .shell.rail-hidden .rail.is-open { display: flex; }
  .rail:not(.is-open) { display: none; }
  main { padding-block: 32px 80px; }
}
@media (max-width: 640px) {
  :root { --read-size: 17px; }
  :root[data-size="s"] { --read-size: 15.5px; }
  :root[data-size="l"] { --read-size: 18.5px; }
  .how { grid-template-columns: minmax(0, 1fr); }
  .map-part { grid-template-columns: minmax(0, 1fr); gap: 12px; }
  .pager, .step-nav { grid-template-columns: minmax(0, 1fr); }
  .pager-link.next { text-align: left; }
  .learn ul { grid-template-columns: minmax(0, 1fr); }
  .step-btn.next { grid-column: 1; order: -1; }
  .step-done { grid-column: 1; text-align: left; }
  .rb-label { display: none; }
  .settings { left: max(16px, env(safe-area-inset-left, 0px)); width: auto; }
  .prose details summary { padding-right: 16px; padding-bottom: 46px; }
  .prose details summary::after { top: auto; bottom: 14px; left: 16px; right: auto; }
}


/* Diagram stages: one dark "console" look in both themes, like a network monitor. */
:root {
  --stage: #0e1218;
  --stage-2: #161b23;
  --stage-3: #1f2631;
  --stage-line: #2b3341;
  --stage-wire: #4a5466;
  --stage-ink: #e9edf2;
  --stage-muted: #8c96a5;
  --stage-accent: #8ea8ff;
  --stage-accent-bg: #18233f;
  --stage-hot: #ff8a6b;
  --stage-good: #6fd6a8;
  --stage-warm: #f3c06b;
}

.stage {
  background: radial-gradient(120% 90% at 50% 0%, #141a23 0%, var(--stage) 60%);
  color: var(--stage-ink); border: 1px solid var(--stage-line); border-radius: 14px; overflow: hidden;
  font-family: var(--font-display); line-height: 1.4;
}
.prose .stage { margin-top: 1.6em; margin-bottom: 0.6em; }
.stage-head { display: flex; justify-content: space-between; align-items: center; gap: 12px; padding: 14px 18px; border-bottom: 1px solid var(--stage-line); }
.stage-label { font: 600 11.5px/1.3 var(--font-mono); letter-spacing: 0.12em; text-transform: uppercase; color: var(--stage-muted); }
.stage-meta { display: flex; align-items: center; gap: 10px; }
.stage-clock { font: 600 13px/1 var(--font-mono); font-variant-numeric: tabular-nums; color: var(--stage-ink); white-space: nowrap; }
.stage-body { padding: 14px 12px; overflow-x: auto; }
.stage-svg { display: block; width: 100%; height: auto; min-width: 560px; overflow: visible; }
.stage-status { margin: 0; padding: 12px 18px 14px; font-size: 15px; line-height: 1.5; color: var(--stage-ink); border-top: 1px solid var(--stage-line); min-height: 3.3em; }
.stage-status strong { color: var(--stage-accent); font-weight: 600; }
.stage-controls { display: flex; flex-wrap: wrap; gap: 10px 14px; align-items: center; padding: 12px 18px 14px; border-top: 1px solid var(--stage-line); }
.seg { display: inline-flex; flex-wrap: wrap; align-items: center; gap: 2px; background: var(--stage-2); border: 1px solid var(--stage-line); border-radius: 9px; padding: 3px; }
.seg-label { font: 500 10.5px/1 var(--font-mono); letter-spacing: 0.08em; text-transform: uppercase; color: var(--stage-muted); padding: 0 8px 0 6px; }
.seg-btn { font: 500 13px/1 var(--font-display); color: var(--stage-muted); background: transparent; border: 0; border-radius: 6px; padding: 7px 10px; cursor: pointer; transition: background .2s, color .2s; }
.seg-btn:hover { color: var(--stage-ink); }
.seg-btn[aria-pressed="true"] { background: var(--stage-3); color: var(--stage-ink); box-shadow: inset 0 0 0 1px var(--stage-wire); }
.replay { margin-left: auto; display: inline-flex; align-items: center; gap: 7px; font: 500 13px/1 var(--font-display); color: var(--stage-ink); background: transparent; border: 1px solid var(--stage-line); border-radius: 9px; padding: 8px 12px; cursor: pointer; transition: border-color .2s, background .2s; }
.replay:hover { border-color: var(--stage-accent); background: var(--stage-accent-bg); }
.replay .ico { width: 15px; height: 15px; }
.stage button:focus-visible { outline: 2px solid var(--stage-accent); outline-offset: 2px; }

.ico, .sico { fill: none; stroke: currentColor; stroke-width: 1.7; stroke-linecap: round; stroke-linejoin: round; }

/* SVG parts */
.stage-svg text { font-family: var(--font-display); }
.t-small { fill: var(--stage-muted); font-size: 12px; }
.t-label { fill: var(--stage-ink); font-size: 13px; font-weight: 500; }
.t-msg { fill: var(--stage-ink); font-size: 11.5px; }
.t-mono { font-family: var(--font-mono) !important; font-size: 11.5px; fill: var(--stage-muted); }
.t-big { fill: var(--stage-ink); font-size: 28px; font-weight: 700; font-family: var(--font-mono) !important; }
.t-phase { fill: var(--stage-accent); font-size: 12px; font-weight: 600; }
.t-work { fill: var(--stage-warm); font-size: 11.5px; }
.t-hot { fill: var(--stage-hot); }
.t-good { fill: var(--stage-good); }
.halo { paint-order: stroke; stroke: var(--stage); stroke-width: 5px; stroke-linejoin: round; }
.tile-r { fill: var(--stage-2); stroke: var(--stage-line); stroke-width: 1; transition: fill .3s, stroke .3s; }
.tile-g .sico { color: var(--stage-muted); transition: color .3s; }
.tile-g.on .tile-r { fill: var(--stage-accent-bg); stroke: var(--stage-accent); }
.tile-g.on .sico { color: var(--stage-accent); }
.lifeline { stroke: var(--stage-line); stroke-width: 1.5; stroke-dasharray: 2 6; stroke-linecap: round; }
.wire { stroke: var(--stage-wire); stroke-width: 2.2; stroke-dasharray: 1 8; stroke-linecap: round; fill: none; transition: stroke .3s; }
.wire.on { stroke: var(--stage-accent); }
.msg { stroke: var(--stage-ink); stroke-width: 1.6; }
.msg.back { stroke: var(--stage-accent); }
.pkt { fill: #fff; filter: drop-shadow(0 0 5px rgba(142, 168, 255, .9)); }
.pkt.hot { fill: var(--stage-hot); filter: drop-shadow(0 0 5px rgba(255, 138, 107, .9)); }
.pkt.good { fill: var(--stage-good); filter: drop-shadow(0 0 5px rgba(111, 214, 168, .8)); }
.bracket { stroke: var(--stage-accent); stroke-width: 1.5; fill: none; opacity: .7; }
.work { fill: var(--stage-warm); }
.tick { stroke: var(--stage-line); stroke-width: 1; }
.box { fill: var(--stage-2); stroke: var(--stage-line); stroke-width: 1; transition: fill .3s, stroke .3s; }
.box.on { fill: var(--stage-accent-bg); stroke: var(--stage-accent); }
.box.bad { fill: #3a1c17; stroke: var(--stage-hot); }
.box.good { fill: #12301f; stroke: var(--stage-good); }
.fade-in { animation: fadeIn .45s ease both; }
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }
.flash { animation: flash .7s ease; }
@keyframes flash { 0% { transform: scale(1); } 35% { transform: scale(1.12); } 100% { transform: scale(1); } }
.flash, .pop { transform-box: fill-box; transform-origin: center; }
.pop { animation: pop .35s cubic-bezier(.2, 1.4, .4, 1) both; }
@keyframes pop { from { transform: scale(.4); opacity: 0; } to { transform: scale(1); opacity: 1; } }
.blink { animation: blink 1s ease-in-out infinite; }
@keyframes blink { 50% { opacity: .35; } }

/* Part 2 diagram parts */
.bar-bg { fill: var(--stage-3); }
.bar { fill: var(--stage-accent); transition: fill .3s; }
.bar.warm { fill: var(--stage-warm); }
.bar.hot { fill: var(--stage-hot); }
.zone { fill: rgba(111, 214, 168, .07); stroke: rgba(111, 214, 168, .25); stroke-dasharray: 3 4; }
.zone.warm { fill: rgba(243, 192, 107, .07); stroke: rgba(243, 192, 107, .3); }
.guide { stroke: var(--stage-wire); stroke-width: 1.2; stroke-dasharray: 3 4; }
.mark { fill: var(--stage-accent); stroke: var(--stage); stroke-width: 3; filter: drop-shadow(0 0 6px rgba(142, 168, 255, .8)); }
.mark.hot { fill: var(--stage-hot); filter: drop-shadow(0 0 6px rgba(255, 138, 107, .8)); }
.err-line { fill: none; stroke: var(--stage-hot); stroke-width: 2.2; stroke-linejoin: round; }
.cap { stroke: var(--stage-ink); stroke-width: 1.5; stroke-dasharray: 2 3; }
.qsq { fill: var(--stage-3); stroke: var(--stage-line); }
.qsq.serving, .qsq.busy { fill: var(--stage-accent); stroke: none; }
.qsq.busy { fill: var(--stage-warm); }
.box.warm { fill: #2c2414; stroke: var(--stage-warm); }
.pkt.warm { fill: var(--stage-warm); filter: drop-shadow(0 0 5px rgba(243, 192, 107, .8)); }
.pkt.dim { fill: var(--stage-muted); filter: none; animation: blink 1s ease-in-out infinite; }
.t-warm { fill: var(--stage-warm); }
.t-ink { fill: #0d1117; font-weight: 600; }
.msg.bad { stroke: var(--stage-hot); }
.msg.good { stroke: var(--stage-good); }
.fail-zone { fill: rgba(255, 138, 107, .08); stroke: var(--stage-hot); stroke-dasharray: 4 4; }
.tile-g.off .tile-r { fill: #2a1714; stroke: var(--stage-hot); }
.tile-g.off .sico { color: var(--stage-hot); }
.wrow { display: grid; grid-template-columns: auto minmax(0, 1fr) 64px; gap: 14px; align-items: center; padding: 6px 12px 2px; font-size: 13.5px; color: var(--stage-muted); }
.wrow input[type="range"] { width: 100%; accent-color: var(--stage-accent); }
.wrow output { font: 600 13px/1 var(--font-mono); color: var(--stage-ink); text-align: right; }

/* Part 3 diagram parts */
.crowd { fill: var(--stage-wire); }
.person { fill: var(--stage-2); stroke: var(--stage-line); stroke-width: 1.5; transition: fill .3s, stroke .3s; }
.person.on { stroke: var(--stage-accent); }
.person.good { fill: #12301f; stroke: var(--stage-good); }
.wire.hidden-edge { opacity: 0; }
.wire.good { stroke: var(--stage-good); opacity: 1; }
.pg.dirty { fill: #3a2a12; stroke: var(--stage-warm); }
.fillbar { fill: var(--stage-accent); transition: width .2s; }
.bit { fill: var(--stage-3); stroke: var(--stage-line); transition: fill .25s, stroke .25s; }
.bit.set { fill: var(--stage-accent); stroke: none; }
.bit.hitbit { stroke: #fff; stroke-width: 2; }
.bit.missbit { fill: #3a1c17; stroke: var(--stage-hot); stroke-width: 2; }
.bit.flashbit { stroke: var(--stage-good); stroke-width: 2; }
.bl-line { stroke-width: 1.5; stroke-dasharray: 3 4; }
.bl-line.add { stroke: var(--stage-good); } .bl-line.yes { stroke: var(--stage-ink); } .bl-line.no { stroke: var(--stage-hot); }
.bloom-row, .ix-q { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; padding: 6px 12px; font-size: 13.5px; color: var(--stage-muted); }
.bloom-row input, .ix-q input { flex: 1 1 160px; min-width: 0; padding: 8px 10px; border-radius: 8px; border: 1px solid var(--stage-line); background: var(--stage-2); color: var(--stage-ink); font: 500 14px/1.2 var(--font-mono); outline: none; }
.bloom-row input:focus, .ix-q input:focus { border-color: var(--stage-accent); }
.bl-btn { border: 1px solid var(--stage-line) !important; }
.bl-btn.on { background: var(--stage-3); color: var(--stage-ink); }
.bloom-mem { margin: 4px 12px 0; font-size: 13px; color: var(--stage-muted); }
.bloom-mem code, .ix-toks code { font: 500 12px/1 var(--font-mono); color: var(--stage-ink); background: var(--stage-3); padding: 3px 6px; border-radius: 5px; margin-right: 2px; }
.bloom-pre, .ix-chips { display: flex; flex-wrap: wrap; gap: 6px; align-items: center; padding: 8px 12px 4px; font-size: 13px; color: var(--stage-muted); }
.bl-chip { border: 1px solid var(--stage-line) !important; font-family: var(--font-mono) !important; font-size: 12px !important; }
.bl-chip span { color: var(--stage-muted); font-family: var(--font-display); margin-left: 4px; }
.ix-toks { margin: 6px 12px 10px; font-size: 13px; color: var(--stage-muted); }
.ix-grid { display: grid; grid-template-columns: minmax(0, 1.15fr) minmax(0, 1fr); gap: 14px; padding: 0 12px 6px; }
.ix-posts { display: grid; gap: 6px; align-content: start; }
.ix-post { display: grid; grid-template-columns: 22px minmax(0, 1fr); gap: 8px; padding: 8px 10px; border-radius: 8px; background: var(--stage-2); border: 1px solid var(--stage-line); font-size: 13.5px; line-height: 1.4; color: var(--stage-ink); transition: opacity .3s, border-color .3s, background .3s; }
.ix-post b { font: 600 12px/1.4 var(--font-mono); color: var(--stage-muted); }
.ix-post.dim { opacity: .4; }
.ix-post.hit { border-color: var(--stage-good); background: #12261c; }
.ix-post mark { background: rgba(142, 168, 255, .28); color: #fff; border-radius: 3px; padding: 0 2px; }
.ix-post.pulse { animation: flash .6s ease; }
.ix-terms { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 4px 10px; align-content: start; }
.ix-term { display: flex; align-items: center; justify-content: space-between; gap: 6px; padding: 4px 8px; border-radius: 6px; font: 500 12px/1.3 var(--font-mono); color: var(--stage-muted); border: 1px solid transparent; transition: background .25s, border-color .25s, color .25s, opacity .3s, transform .3s; }
.ix-term.on { background: var(--stage-accent-bg); border-color: var(--stage-accent); color: var(--stage-ink); }
.ix-term.pre { opacity: 0; transform: translateX(8px); }
.ix-list { display: inline-flex; gap: 3px; }
.ix-list i { font-style: normal; min-width: 16px; text-align: center; padding: 1px 3px; border-radius: 4px; background: var(--stage-3); color: var(--stage-ink); }
.ix-term.on .ix-list i { background: var(--stage-accent); color: #0d1117; }
@media (max-width: 600px) { .ix-grid { grid-template-columns: minmax(0, 1fr); } }

/* Part 4 diagram parts */
.replyline { stroke: var(--stage-good); stroke-width: 2; stroke-dasharray: 4 4; }
.lane { fill: var(--stage-2); }
.tbar.fg { fill: var(--stage-accent); }
.tbar.bg { fill: var(--stage-wire); }
.tbar.slow { fill: var(--stage-hot); }
.tbar.bg.slow { fill: #7a4a3c; }
.ptr { fill: none; stroke-width: 2; stroke-dasharray: 3 3; marker-end: none; }
.ptr.on { stroke: var(--stage-accent); } .ptr.warm { stroke: var(--stage-warm); }
.seg-0 { fill: var(--stage-3); } .seg-time { fill: #1d2a4d; stroke: var(--stage-accent); }
.seg-machine { fill: #2c2414; stroke: var(--stage-warm); } .seg-seq { fill: #12301f; stroke: var(--stage-good); }
.sf-list { display: grid; gap: 5px; padding: 4px 12px 6px; min-height: 140px; align-content: start; }
.sf-row { display: flex; justify-content: space-between; gap: 10px; flex-wrap: wrap; padding: 7px 10px; border-radius: 7px; background: var(--stage-2); border: 1px solid var(--stage-line); font-size: 12.5px; color: var(--stage-muted); }
.sf-row code { font: 600 13px/1.3 var(--font-mono); color: var(--stage-ink); }
@media (prefers-reduced-motion: no-preference) {
  .pop-in { animation: popIn .35s cubic-bezier(.2, 1.3, .4, 1) both; }
  @keyframes popIn { from { opacity: 0; transform: translateY(-4px); } to { opacity: 1; transform: none; } }
}

/* Part 5 diagram parts */
.chipc { stroke: none; } .chipc.a { fill: var(--stage-accent); } .chipc.b { fill: var(--stage-good); } .chipc.c { fill: var(--stage-hot); }
.chipc.sel { stroke: #fff; stroke-width: 2; }
.kdot { stroke: var(--stage); stroke-width: 2; transition: fill .3s; }
.kdot.s0, .kbar.s0 { fill: var(--stage-accent); } .kdot.s1, .kbar.s1 { fill: var(--stage-good); } .kdot.s2, .kbar.s2 { fill: var(--stage-warm); }
.kdot.s3, .kbar.s3 { fill: #c9a7ff; } .kdot.s4, .kbar.s4 { fill: var(--stage-hot); }
.kdot.moved { stroke: #fff; stroke-width: 2.5; }
.wire.cut { stroke: var(--stage-hot); opacity: .5; }
.wire.dim-edge { opacity: .4; }

/* Part 6 diagram parts */
.hbar { fill: var(--stage-accent); opacity: .85; }
.mk-avg { stroke: var(--stage-warm); stroke-width: 2; stroke-dasharray: 4 3; } .mk-avgt { fill: var(--stage-warm); }
.mk-p50 { stroke: var(--stage-good); stroke-width: 2; stroke-dasharray: 4 3; } .mk-p50t { fill: var(--stage-good); }
.mk-p99 { stroke: var(--stage-hot); stroke-width: 2; stroke-dasharray: 4 3; } .mk-p99t { fill: var(--stage-hot); }
.tbar.hedgebar { fill: var(--stage-good); }
.win { fill: rgba(142, 168, 255, .05); stroke: var(--stage-line); stroke-dasharray: 3 4; }
.rq.ok { fill: var(--stage-good); } .rq.no { fill: var(--stage-hot); opacity: .8; }
.bucket { fill: rgba(142, 168, 255, .05); stroke: var(--stage-wire); stroke-width: 2.5; stroke-linejoin: round; }
.tok { fill: var(--stage-3); stroke: var(--stage-line); transition: fill .25s; }
.tok.full { fill: var(--stage-warm); stroke: none; } .tok.part { fill: #5a4720; }
.g-line.budget { stroke: var(--stage-accent); stroke-dasharray: none; }
.rnode { fill: var(--stage-2); stroke: var(--stage-wire); stroke-width: 2; transition: fill .3s, stroke .3s; }
.rnode.leader { fill: var(--stage-accent-bg); stroke: var(--stage-accent); stroke-width: 3; }
.rnode.candidate { fill: #2c2414; stroke: var(--stage-warm); stroke-width: 3; }
.rnode.down { fill: #2a1714; stroke: var(--stage-hot); stroke-dasharray: 4 3; }

/* Part 7 diagram parts */
.gcell { fill: transparent; stroke: var(--stage-line); stroke-width: 1; }
.gcell.on { fill: rgba(142, 168, 255, .08); stroke: var(--stage-accent); }
.gcell.home { fill: rgba(142, 168, 255, .16); }
.drv { fill: var(--stage-wire); transition: fill .2s; }
.drv.seen { fill: var(--stage-warm); }
.drv.best { fill: var(--stage-good); stroke: #fff; stroke-width: 2; }
.rider { fill: var(--stage-good); stroke: var(--stage); stroke-width: 3; filter: drop-shadow(0 0 6px rgba(111, 214, 168, .8)); }

/* Part 8 widget parts */
.phase { transition: width .2s; }
.phase.p1 { fill: var(--stage-accent); } .phase.p2 { fill: #c9a7ff; } .phase.p3 { fill: var(--stage-warm); }
.phase.p4 { fill: var(--stage-good); } .phase.p5 { fill: #5fb3d9; } .phase.p6 { fill: var(--stage-hot); }
.drill { padding: 6px 12px 4px; display: grid; gap: 4px; }
.drill-n { margin: 0; font: 500 11px/1.3 var(--font-mono); letter-spacing: .08em; text-transform: uppercase; color: var(--stage-muted); }
.drill-q { margin: 0 0 4px; font-size: 16px; line-height: 1.5; color: var(--stage-ink); }
.drill-unit { font: 500 12.5px/1 var(--font-mono); color: var(--stage-muted); }
.drill-fb { margin: 4px 0; padding: 10px 12px; border-radius: 8px; font-size: 14px; line-height: 1.5; color: var(--stage-ink); min-height: 1.5em; }
.drill-fb:empty { display: none; }
.drill-fb.good { background: #12301f; border: 1px solid var(--stage-good); }
.drill-fb.ok { background: var(--stage-2); border: 1px solid var(--stage-line); }
.drill-fb.bad { background: #3a1c17; border: 1px solid var(--stage-hot); }
.drill-fb strong, .drill-fb b { color: #fff; }

/* Pages and tree (index lesson) */
.pg { fill: var(--stage-3); stroke: var(--stage-line); transition: fill .15s; }
.pg.scanned { fill: #222a36; }
.pg.cur { fill: var(--stage-accent); }
.pg.hit { fill: var(--stage-good); }
.edge { stroke: var(--stage-line); stroke-width: 1.5; }
.edge.on { stroke: var(--stage-accent); stroke-width: 2; }

/* Queue (fan-out lesson) */
.q { fill: var(--stage-2); stroke: var(--stage-line); }
.q-item { fill: var(--stage-accent); }
.q-big { fill: var(--stage-hot); }
.feed { fill: var(--stage-3); stroke: var(--stage-line); transition: fill .25s; }
.feed.lit { fill: var(--stage-accent); }
.feed.hot { fill: var(--stage-hot); }
.feed.ring { stroke: var(--stage-good); stroke-width: 2.5; }

/* Latency bars */
.lat { display: grid; gap: 9px; padding: 4px 6px; min-width: 0; }
.lat-row { display: grid; grid-template-columns: minmax(0, 210px) minmax(0, 1fr) 96px; gap: 12px; align-items: center; font-size: 13.5px; }
.lat-name { color: var(--stage-ink); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.lat-track { height: 10px; background: var(--stage-2); border-radius: 5px; overflow: hidden; }
.lat-bar { height: 100%; width: 0; border-radius: 5px; background: var(--stage-accent); }
.lat-bar.disk { background: var(--stage-warm); }
.lat-bar.net { background: var(--stage-hot); }
.lat-val { font: 600 12.5px/1 var(--font-mono); color: var(--stage-ink); text-align: right; font-variant-numeric: tabular-nums; white-space: nowrap; }
.lat-legend { display: flex; flex-wrap: wrap; gap: 6px 16px; padding: 10px 6px 0; font-size: 12.5px; color: var(--stage-muted); }
.lat-legend i { display: inline-block; width: 10px; height: 10px; border-radius: 3px; margin-right: 6px; vertical-align: -1px; background: var(--stage-accent); }
.lat-legend i.disk { background: var(--stage-warm); }
.lat-legend i.net { background: var(--stage-hot); }
@media (max-width: 560px) {
  .lat-row { grid-template-columns: minmax(0, 1fr) 84px; }
  .lat-track { grid-column: 1 / -1; grid-row: 2; }
}

/* Napkin calculator */
.nap { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1.1fr); gap: 22px; padding: 6px; }
.nap-inputs { display: grid; gap: 14px; align-content: start; }
.nap-in { display: grid; gap: 6px; }
.nap-in-top { display: flex; justify-content: space-between; gap: 8px; font-size: 13.5px; color: var(--stage-muted); }
.nap-in-top output { font: 600 13px/1.3 var(--font-mono); color: var(--stage-ink); }
.nap-in input[type="range"] { width: 100%; accent-color: var(--stage-accent); }
.nap-outs { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px; align-content: start; }
.nap-card { background: var(--stage-2); border: 1px solid var(--stage-line); border-radius: 10px; padding: 11px 13px; }
.nap-card span { display: block; font-size: 12px; color: var(--stage-muted); line-height: 1.3; }
.nap-card b { display: block; margin-top: 6px; font: 700 21px/1.1 var(--font-mono); color: var(--stage-ink); font-variant-numeric: tabular-nums; }
.nap-card.key b { color: var(--stage-hot); }
.nap-bars { grid-column: 1 / -1; display: grid; gap: 7px; padding-top: 4px; }
.nap-bar { display: grid; grid-template-columns: 58px minmax(0, 1fr) 70px; gap: 10px; align-items: center; font-size: 12.5px; color: var(--stage-muted); }
.nap-bar div { height: 9px; background: var(--stage-3); border-radius: 5px; overflow: hidden; }
.nap-bar i { display: block; height: 100%; background: var(--stage-accent); border-radius: 5px; transition: width .5s cubic-bezier(.2, .7, .2, 1); }
.nap-bar.photos i { background: var(--stage-hot); }
.nap-bar em { font: normal 600 12px/1 var(--font-mono); color: var(--stage-ink); text-align: right; }
.nap-verdict { grid-column: 1 / -1; margin: 4px 0 0; padding: 0; list-style: none; display: grid; gap: 7px; font-size: 14px; line-height: 1.45; }
.nap-verdict li { padding-left: 18px; position: relative; }
.nap-verdict li::before { content: ""; position: absolute; left: 2px; top: .5em; width: 7px; height: 7px; border-radius: 50%; background: var(--stage-accent); }
@media (max-width: 640px) { .nap { grid-template-columns: minmax(0, 1fr); } }

/* Cursor vs offset */
.cur { display: grid; grid-template-columns: minmax(0, 300px) minmax(0, 1fr); gap: 20px; padding: 6px; }
.cur-list { position: relative; }
.cur-post { position: absolute; left: 0; right: 0; height: 24px; display: flex; align-items: center; gap: 10px; padding: 0 10px; border-radius: 6px; background: var(--stage-2); border: 1px solid var(--stage-line); font-size: 13px; color: var(--stage-muted); transition: top .6s cubic-bezier(.3, .8, .3, 1), opacity .5s, background .3s, border-color .3s, color .3s; }
.cur-post b { font: 600 12px/1 var(--font-mono); color: var(--stage-ink); }
.cur-post.seen { color: var(--stage-ink); }
.cur-post.new { border-color: var(--stage-good); }
.cur-post.again { background: #3a1c17; border-color: var(--stage-hot); color: var(--stage-ink); }
.cur-post.again::after { content: "seen again"; margin-left: auto; font: 600 10.5px/1 var(--font-mono); text-transform: uppercase; letter-spacing: .06em; color: var(--stage-hot); }
.cur-br { position: absolute; left: -8px; right: -8px; border: 1.5px solid var(--stage-accent); border-radius: 9px; pointer-events: none; transition: top .5s cubic-bezier(.3, .8, .3, 1), height .5s, opacity .4s; }
.cur-br span { position: absolute; top: -9px; right: 10px; background: var(--stage); padding: 0 6px; font: 600 10.5px/1.6 var(--font-mono); text-transform: uppercase; letter-spacing: .08em; color: var(--stage-accent); }
.cur-br.p2 { border-color: var(--stage-warm); }
.cur-br.p2 span { color: var(--stage-warm); }
.cur-side { display: grid; gap: 12px; align-content: start; font-size: 14px; color: var(--stage-muted); }
.cur-req { font: 600 12.5px/1.5 var(--font-mono); color: var(--stage-ink); background: var(--stage-2); border: 1px solid var(--stage-line); border-radius: 8px; padding: 10px 12px; overflow-wrap: anywhere; }
@media (max-width: 600px) { .cur { grid-template-columns: minmax(0, 1fr); } }

/* Lesson trace (waterfall of sections) */
.trace { padding: 12px 18px 16px; }
.tr-axis, .trace-row { display: grid; grid-template-columns: 24px minmax(0, 36%) minmax(0, 1fr); align-items: center; }
.tr-axis { font: 500 10.5px/1 var(--font-mono); letter-spacing: .06em; text-transform: uppercase; color: var(--stage-muted); padding-bottom: 8px; }
.tr-ticks { position: relative; height: 12px; }
.tr-ticks span { position: absolute; top: 0; transform: translateX(-50%); text-transform: none; letter-spacing: 0; white-space: nowrap; }
.tr-ticks span:first-child { transform: none; }
.tr-ticks span:last-child { transform: translateX(-100%); }
.trace-row { width: 100%; height: 25px; padding: 0; border: 0; border-radius: 5px; background: none; color: var(--stage-muted); font: 400 13px/1 var(--font-display); text-align: left; cursor: pointer; transition: color .25s, background .25s; }
.trace-row:hover { background: rgba(255, 255, 255, .035); color: var(--stage-ink); }
.tr-i { font: 500 10.5px/1 var(--font-mono); color: var(--stage-wire); transition: color .25s; }
.tr-name { white-space: nowrap; overflow: hidden; text-overflow: ellipsis; padding-right: 14px; }
.tr-track { position: relative; height: 100%; border-left: 1px solid var(--stage-line); background: repeating-linear-gradient(to right, transparent 0 calc(25% - 1px), rgba(255, 255, 255, .045) calc(25% - 1px) 25%); }
.tr-bar { position: absolute; top: 50%; height: 7px; margin-top: -3.5px; min-width: 3px; border-radius: 2px; background: var(--stage-3); overflow: hidden; transition: background .3s; }
.tr-glint { display: none; position: absolute; top: 0; bottom: 0; width: 45%; background: linear-gradient(90deg, transparent, rgba(255, 255, 255, .75), transparent); }
.tr-play { position: absolute; top: 0; bottom: 0; width: 0; border-left: 1.5px solid rgba(255, 138, 107, .75); pointer-events: none; transition: left .25s linear; }
.trace-row.is-done { color: #c3cad5; }
.trace-row.is-done .tr-bar { background: #56627a; }
.trace-row.is-current { color: #fff; font-weight: 600; }
.trace-row.is-current .tr-i { color: var(--stage-accent); }
.trace-row.is-current .tr-bar { background: var(--stage-accent); box-shadow: 0 0 12px rgba(142, 168, 255, .55); }
.trace-row.is-current .tr-glint { display: block; }
.trace-row.is-current .tr-play::after { content: ""; position: absolute; top: 50%; left: -5px; width: 8px; height: 8px; margin-top: -4px; border-radius: 50%; background: var(--stage-hot); box-shadow: 0 0 10px rgba(255, 138, 107, .9); }
.live-dot { width: 7px; height: 7px; border-radius: 50%; background: var(--stage-hot); box-shadow: 0 0 8px rgba(255, 138, 107, .9); flex: none; }
.trace-now { font: 500 12px/1.2 var(--font-mono); color: var(--stage-ink); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; max-width: 40ch; }
@media (max-width: 560px) {
  .trace { padding: 10px 12px 14px; }
  .tr-axis, .trace-row { grid-template-columns: 0 minmax(0, 46%) minmax(0, 1fr); }
  .tr-i { visibility: hidden; }
  .trace-row { font-size: 12.5px; }
  .tr-ticks span:nth-child(2), .tr-ticks span:nth-child(4) { display: none; }
  .trace-now { max-width: 22ch; }
}

/* Home growth curve */
.growth-svg { min-width: 620px; }
.gridline { stroke: var(--stage-line); stroke-width: 1; stroke-dasharray: 2 5; }
.g-line { fill: none; stroke: var(--stage-accent); stroke-width: 2.5; stroke-linecap: round; }
.g-tail { fill: none; stroke: var(--stage-wire); stroke-width: 2; stroke-dasharray: 2 6; stroke-linecap: round; }
.st-g { cursor: pointer; outline: none; }
.st { fill: var(--stage); stroke: var(--stage-wire); stroke-width: 2; transition: stroke .2s, fill .2s; }
.st-g:hover .st, .st-g:focus-visible .st { stroke: var(--stage-ink); }
.st-g.ready .st { fill: var(--stage-accent); stroke: var(--stage-accent); }
.st-ring { fill: none; stroke: var(--stage-accent); stroke-width: 1.5; }
.t-st { fill: var(--stage-ink); font-size: 12.5px; font-weight: 600; }
.st-g:not(.ready) .t-st { fill: #b8c0cc; font-weight: 500; }
.here { fill: var(--stage-accent-bg); stroke: var(--stage-accent); stroke-width: 1; }
.t-here { fill: var(--stage-accent); font: 600 10.5px var(--font-mono); }

/* Flowing pipeline */
.flow { position: relative; display: grid; gap: 10px; padding: 6px; }
.flow-row { position: relative; z-index: 1; display: grid; grid-template-columns: 40px minmax(0, 1fr); gap: 14px; align-items: center; }
.flow-tile { width: 40px; height: 40px; border-radius: 11px; display: grid; place-items: center; background: var(--stage-2); border: 1px solid var(--stage-line); color: var(--stage-accent); }
.flow-tile .ico { width: 19px; height: 19px; }
.flow-row b { display: block; font-size: 14px; font-weight: 600; color: var(--stage-ink); }
.flow-row div span { display: block; font-size: 12.5px; color: var(--stage-muted); margin-top: 2px; }
.flow-line { position: absolute; left: 25px; top: 26px; bottom: 26px; width: 2px; background: radial-gradient(circle, var(--stage-wire) 1px, transparent 1.6px) 0 0 / 2px 8px repeat-y; }
.flow-pkt { position: absolute; left: -3px; width: 8px; height: 8px; border-radius: 50%; background: #fff; box-shadow: 0 0 8px rgba(142, 168, 255, .9); top: 0; }

@media (prefers-reduced-motion: no-preference) {
  .g-line { stroke-dasharray: 1; stroke-dashoffset: 1; animation: draw 2.2s cubic-bezier(.4, 0, .2, 1) .2s forwards; }
  @keyframes draw { to { stroke-dashoffset: 0; } }
  .st-ring { animation: ring 2.2s ease-out infinite; transform-box: fill-box; transform-origin: center; }
  @keyframes ring { from { transform: scale(.7); opacity: 1; } to { transform: scale(2.2); opacity: 0; } }
  .trace-row.is-current .tr-glint { animation: glint 1.7s linear infinite; }
  @keyframes glint { from { transform: translateX(-110%); } to { transform: translateX(240%); } }
  .trace-row.is-current .tr-play::after, .live-dot { animation: ping 1.8s ease-in-out infinite; }
  @keyframes ping { 50% { opacity: .35; } }
  .flow-pkt { animation: flowDown 3.3s linear infinite; }
  .flow-pkt:nth-child(2) { animation-delay: -1.1s; }
  .flow-pkt:nth-child(3) { animation-delay: -2.2s; }
  @keyframes flowDown { from { top: 0; } to { top: 100%; } }
}
@media (prefers-reduced-motion: reduce) { .flow-pkt { display: none; } }
@media (prefers-reduced-motion: reduce) {
  .fade-in, .flash, .pop, .blink { animation: none !important; transition: none !important; }
}

/* Part 9: scene and chart engines (real-world and going-deeper diagrams) */
.sc-zone { fill: rgba(255, 255, 255, .025); stroke: var(--stage-line); stroke-dasharray: 3 5; }
.sc-zone.hot { fill: rgba(255, 138, 107, .06); stroke: rgba(255, 138, 107, .45); }
.sc-zone.good { fill: rgba(111, 214, 168, .05); stroke: rgba(111, 214, 168, .35); }
.sc-e { stroke: var(--stage-wire); stroke-width: 2; stroke-dasharray: 1 7; stroke-linecap: round; transition: stroke .3s, opacity .3s; }
.sc-e.on { stroke: var(--stage-accent); }
.sc-e.good { stroke: var(--stage-good); }
.sc-e.bad { stroke: var(--stage-hot); stroke-dasharray: 6 5; }
.sc-e.warm { stroke: var(--stage-warm); }
.sc-e.dead { stroke: var(--stage-hot); opacity: .25; stroke-dasharray: 2 8; }
.sc-e.ghost { opacity: 0; }
.sc-n .tile-r, .sc-n .sico { transition: fill .35s, stroke .35s, color .35s, opacity .35s; }
.sc-n.is-on .tile-r { fill: var(--stage-accent-bg); stroke: var(--stage-accent); }
.sc-n.is-on .sico { color: var(--stage-accent); }
.sc-n.is-good .tile-r { fill: rgba(111, 214, 168, .1); stroke: var(--stage-good); }
.sc-n.is-good .sico { color: var(--stage-good); }
.sc-n.is-warm .tile-r { fill: rgba(243, 192, 107, .1); stroke: var(--stage-warm); }
.sc-n.is-warm .sico { color: var(--stage-warm); }
.sc-n.is-hot .tile-r { fill: rgba(255, 138, 107, .14); stroke: var(--stage-hot); }
.sc-n.is-hot .sico { color: var(--stage-hot); }
.sc-n.is-down .tile-r { fill: var(--stage); stroke: var(--stage-hot); stroke-dasharray: 4 4; }
.sc-n.is-down .sico { color: var(--stage-hot); opacity: .5; }
.sc-n.is-down .t-label { fill: var(--stage-hot); }
.ch-line { fill: none; stroke: var(--stage-accent); stroke-width: 2.4; stroke-linecap: round; stroke-linejoin: round; }
.ch-line.hot { stroke: var(--stage-hot); }
.ch-line.good { stroke: var(--stage-good); }
.ch-line.warm { stroke: var(--stage-warm); }
.ch-line.muted { stroke: var(--stage-muted); stroke-width: 1.6; }
.ch-lab { font-size: 11px; }
.ch-lab.hot { fill: var(--stage-hot); } .ch-lab.good { fill: var(--stage-good); } .ch-lab.warm { fill: var(--stage-warm); }
.ch-lab:not(.hot):not(.good):not(.warm):not(.muted) { fill: var(--stage-accent); }
.ch-dot { fill: var(--stage-warm); stroke: var(--stage); stroke-width: 2; }
.ch-dot.hot { fill: var(--stage-hot); } .ch-dot.good { fill: var(--stage-good); }
.ch-band { fill: rgba(255, 138, 107, .07); }
.ch-band.good { fill: rgba(111, 214, 168, .06); }
.ch-band.warm { fill: rgba(243, 192, 107, .07); }
@media (prefers-reduced-motion: reduce) { .sc-n .tile-r, .sc-n .sico, .sc-e { transition: none; } }



/* The Chirp simulation page. Uses the site's tokens; dashboards use the dark stage look. */
.sim { max-width: 1140px; margin: 0 auto; }
.sim-head, .sim-steps { max-width: 1140px; }
.sim-head h1 { font-weight: 600; font-size: clamp(30px, 4.6vw, 42px); line-height: 1.1; letter-spacing: -0.035em; margin: 0 0 12px; text-wrap: balance; }
.sim-lede { margin: 0 0 24px; font-size: 17px; line-height: 1.6; color: var(--soft-ink); max-width: 40em; }

.sim-steps { list-style: none; margin: 0 0 26px; padding: 0; display: grid; grid-template-columns: repeat(auto-fit, minmax(132px, 1fr)); gap: 8px; }
.sim-step button { width: 100%; display: grid; gap: 2px; text-align: left; padding: 10px 12px; border-radius: 10px; border: 1px solid var(--line); background: var(--panel); color: var(--ink); font: 500 14px/1.3 var(--font-display); cursor: pointer; transition: border-color .2s, transform .25s var(--ease); }
.sim-step button:hover:not(:disabled) { border-color: color-mix(in srgb, var(--accent) 50%, var(--line)); }
.sim-step button:disabled { opacity: .5; cursor: not-allowed; }
.sim-step-n { font: 500 10.5px/1.3 var(--font-mono); letter-spacing: .08em; text-transform: uppercase; color: var(--muted); }
.sim-step small { color: var(--muted); font-size: 12px; }
.sim-step.is-done button { border-color: color-mix(in srgb, var(--good) 45%, var(--line)); }
.sim-step.is-done .sim-step-n::after { content: " ✓"; color: var(--good); }
.sim-step.is-current button { border-color: var(--accent); background: var(--accent-soft); }

.sim-stage { display: grid; gap: 16px; }
.sim-story { margin: 0; font-family: var(--font-serif); font-size: 18px; line-height: 1.6; color: var(--soft-ink); border-left: 2px solid var(--accent); padding: 2px 0 2px 16px; }
.sim-story strong { font-family: var(--font-display); color: var(--ink); }
.sim-warn { margin: 0; padding: 10px 14px; border-radius: 10px; background: var(--amber-soft); color: var(--amber); font-size: 14px; }
.sim-dec { margin: 0; padding: 14px 16px 16px; border: 1px solid var(--line); border-radius: 12px; background: var(--panel); }
.sim-dec legend { padding: 0 6px; font-weight: 600; font-size: 15.5px; }
.sim-lesson { margin-left: 6px; font: 500 11px/1 var(--font-mono); letter-spacing: .04em; text-decoration: none; color: var(--accent); background: var(--accent-soft); padding: 3px 7px; border-radius: 999px; }
.sim-opts { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 8px; margin-top: 6px; }
.sim-opt { position: relative; display: grid; gap: 4px; padding: 12px 14px 12px 38px; border: 1px solid var(--line); border-radius: 10px; cursor: pointer; transition: border-color .2s, background .2s; }
.sim-opt:hover { border-color: color-mix(in srgb, var(--accent) 45%, var(--line)); }
.sim-opt input { position: absolute; left: 13px; top: 15px; accent-color: var(--accent); }
.sim-opt.is-on { border-color: var(--accent); background: var(--accent-soft); }
.sim-opt-t { font-weight: 500; font-size: 14.5px; line-height: 1.3; }
.sim-opt-n { font-size: 13px; line-height: 1.45; color: var(--muted); }
.sim-run { justify-self: start; border: 0; cursor: pointer; }
.sim-run:disabled { opacity: .45; cursor: not-allowed; }

.sim-dash, .sim-sum { margin-top: 6px; }
.sim-tiles { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 10px; padding: 14px 16px; }
.sim-tile { padding: 12px 14px; border-radius: 10px; background: var(--stage-2); border: 1px solid var(--stage-line); }
.sim-tile span { display: block; font-size: 12px; color: var(--stage-muted); }
.sim-tile b { display: block; margin-top: 6px; font: 700 22px/1.1 var(--font-mono); color: var(--stage-ink); font-variant-numeric: tabular-nums; }
.sim-tile.good b { color: var(--stage-good); } .sim-tile.warn b { color: var(--stage-warm); } .sim-tile.bad b { color: var(--stage-hot); }
.sim-incidents { display: grid; gap: 10px; padding: 0 16px 16px; }
.sim-none { margin: 0; color: var(--stage-muted); font-size: 14px; }
.sim-inc { padding: 12px 14px; border-radius: 10px; border: 1px solid var(--stage-line); background: var(--stage-2); color: var(--stage-ink); font-size: 14px; line-height: 1.5; }
.sim-inc h3 { margin: 6px 0 4px; font-size: 15.5px; font-weight: 600; }
.sim-inc p { margin: 0; }
.sim-inc p + p { margin-top: 6px; }
.sim-inc a { color: var(--stage-accent); }
.sim-inc code { font: 500 12px var(--font-mono); background: var(--stage-3); padding: 1px 5px; border-radius: 4px; }
.sim-inc-top { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }
.sim-sev { font: 600 10.5px/1 var(--font-mono); letter-spacing: .08em; text-transform: uppercase; padding: 4px 7px; border-radius: 5px; background: var(--stage-3); color: var(--stage-muted); }
.sim-inc.outage { border-color: var(--stage-hot); background: #2a1714; } .sim-inc.outage .sim-sev { background: var(--stage-hot); color: #0d1117; }
.sim-inc.major { border-color: #8a4a3a; } .sim-inc.major .sim-sev { background: #5a2c22; color: var(--stage-hot); }
.sim-inc.minor .sim-sev { background: #3a2f17; color: var(--stage-warm); }
.sim-inc.win { border-color: #2f6b52; background: #11261d; } .sim-inc.win .sim-sev { background: #1b4434; color: var(--stage-good); }
.sim-later { font: 600 11px/1 var(--font-mono); color: var(--stage-warm); padding: 4px 7px; border-radius: 5px; border: 1px dashed var(--stage-warm); }
.sim-cause { color: var(--stage-muted); font-size: 13px; }
.sim-cause b { color: var(--stage-ink); font-weight: 500; }
.sim-nav { margin-top: 12px; }
.sim-nav .btn { border: 0; cursor: pointer; }

.sim-grade { display: flex; gap: 18px; align-items: center; padding: 16px; color: var(--stage-ink); }
.sim-grade > b { flex: none; width: 72px; height: 72px; border-radius: 18px; display: grid; place-items: center; font: 700 38px/1 var(--font-display); background: var(--stage-accent-bg); color: var(--stage-accent); border: 1px solid var(--stage-accent); }
.sim-grade p { margin: 0; font-size: 14px; line-height: 1.5; color: var(--stage-muted); }
.sim-score { font: 600 18px/1.3 var(--font-display) !important; color: var(--stage-ink) !important; margin-bottom: 4px !important; }
.sim-score .up { color: var(--stage-good); font-size: 14px; } .sim-score .down { color: var(--stage-hot); font-size: 14px; }
.sim-timeline { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 10px; }
.sim-col { display: grid; gap: 6px; align-content: start; padding: 12px; border: 1px solid var(--line); border-radius: 12px; background: var(--panel); }
.sim-col-h { margin: 0 0 4px; font-weight: 600; font-size: 14.5px; }
.sim-col-h small { display: block; font-weight: 400; font-size: 12px; color: var(--muted); }
.sim-chip { margin: 0; padding: 7px 9px; border-radius: 8px; background: var(--paper); border: 1px solid var(--line); font-size: 13px; line-height: 1.35; }
.sim-chip span { display: block; font: 500 10.5px/1.3 var(--font-mono); letter-spacing: .05em; text-transform: uppercase; color: var(--muted); }
.sim-chip.inc { border-color: color-mix(in srgb, var(--amber) 40%, var(--line)); }
.sim-chip.inc.outage { border-color: #e0785f; }
.sim-from { display: inline !important; margin-left: 6px; color: var(--amber) !important; }
.sim-rewind, .sim-reset { margin-top: 4px; justify-self: start; border: 1px solid var(--line) !important; color: var(--ink) !important; background: var(--panel) !important; }
.sim-note { margin: 0; font-size: 14px; color: var(--muted); }
.sim-link { display: inline-flex; align-items: center; gap: 6px; padding: 8px 12px; border-radius: 9px; background: var(--accent-soft); color: var(--accent) !important; font: 500 14px/1 var(--font-display); background-image: none !important; }

@media (prefers-reduced-motion: no-preference) {
  .sim-in { animation: simIn .5s cubic-bezier(.2, .7, .2, 1) both; }
  @keyframes simIn { from { opacity: 0; transform: translateY(10px) scale(.98); } to { opacity: 1; transform: none; } }
}
@media (max-width: 720px) {
  .sim-steps { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .sim-tiles { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .sim-timeline { grid-template-columns: minmax(0, 1fr); }
}

/* Live architecture diagram */
.sim-grid { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 500px); gap: 22px; align-items: start; }
.sim-side { position: sticky; top: calc(var(--sticky-top) + 12px); }
.sim-side .sim-arch { margin: 0; }
.arch-svg { min-width: 0 !important; }
.arch-cap { min-height: 2.6em; font-size: 14px; }
.abox { fill: var(--stage-2); stroke: var(--stage-wire); stroke-width: 1.4; }
.abox.hot { stroke: var(--stage-warm); }
.abox.pending { fill: transparent; stroke: var(--stage-muted); stroke-dasharray: 5 4; }
.aq { fill: var(--stage-muted); font-size: 22px; }
.anode .sico { color: var(--stage-accent); }
.anode.is-new .abox { stroke: var(--stage-good); stroke-width: 2.4; }
.anode.ghost { opacity: .75; }
.anode.ghost .abox { stroke: var(--stage-good); stroke-dasharray: 5 4; fill: rgba(111, 214, 168, .06); }
.anode.removed { opacity: .55; }
.anode.removed .abox { stroke: var(--stage-hot); stroke-dasharray: 5 4; fill: rgba(255, 138, 107, .08); }
.abadge { fill: var(--stage-3); stroke: var(--stage-line); }
.abadge.hot { fill: #3a2f17; stroke: var(--stage-warm); }
.abadge-t { font-size: 10px !important; fill: var(--stage-ink) !important; }
.aedge { stroke: var(--stage-wire); stroke-width: 1.6; stroke-dasharray: 2 5; fill: none; }
.aedge.repl { stroke: var(--stage-warm); }
.aedge.dual { stroke: var(--stage-hot); }
.aedge.dim { opacity: .5; }
.aedge.ghost { stroke: var(--stage-good); }
.aedge.gone { stroke: var(--stage-hot); opacity: .5; }
.alabel { font-size: 10px !important; }
.adot { fill: #fff; filter: drop-shadow(0 0 3px rgba(142, 168, 255, .9)); }
.adot.hot { fill: var(--stage-hot); } .adot.warm { fill: var(--stage-warm); }
@media (prefers-reduced-motion: no-preference) {
  .anode.is-new { animation: archPop .6s cubic-bezier(.2, 1.3, .4, 1) both; transform-box: fill-box; transform-origin: center; }
  .anode.is-new .abox { animation: archGlow 2.4s ease-out both; }
  @keyframes archPop { from { opacity: 0; transform: scale(.6); } to { opacity: 1; transform: none; } }
  @keyframes archGlow { 0% { filter: drop-shadow(0 0 0 rgba(111, 214, 168, 0)); } 25% { filter: drop-shadow(0 0 10px rgba(111, 214, 168, .9)); } 100% { filter: drop-shadow(0 0 0 rgba(111, 214, 168, 0)); } }
}
@media (max-width: 1100px) {
  .sim-grid { grid-template-columns: minmax(0, 1fr); }
  .sim-side { position: static; order: -1; }
}

/* Hover explainer in the architecture caption */
.arch-cap .pc { display: block; margin-top: 4px; font-size: 13.5px; }
.arch-cap .pc.pro { color: var(--stage-good); }
.arch-cap .pc.con { color: var(--stage-warm); }
.sim-flash { margin: 0; padding: 10px 14px; border-radius: 10px; background: var(--accent-soft); color: var(--ink); font-size: 14.5px; border: 1px solid color-mix(in srgb, var(--accent) 40%, var(--line)); }
.sim-out { margin-top: 22px; }

/* Load colours on the diagram */
.lbar-bg { fill: var(--stage-3); }
.lbar.lb-ok, .rp-bar .lb-ok { fill: var(--stage-good); background: var(--stage-good); }
.lbar.lb-warn, .rp-bar .lb-warn { fill: var(--stage-warm); background: var(--stage-warm); }
.lbar.lb-hot, .rp-bar .lb-hot { fill: var(--stage-hot); background: var(--stage-hot); }
.lt-ok { fill: var(--stage-good) !important; color: var(--stage-good); }
.lt-warn { fill: var(--stage-warm) !important; color: var(--stage-warm); }
.lt-hot, .lt-down { fill: var(--stage-hot) !important; color: var(--stage-hot); }
.anode.lv-ok .abox { stroke: rgba(111, 214, 168, .55); }
.anode.lv-warn .abox { stroke: var(--stage-warm); }
.anode.lv-hot .abox { stroke: var(--stage-hot); fill: #2a1714; }
.anode.lv-down .abox { stroke: var(--stage-hot); stroke-dasharray: 5 4; fill: #1a1210; }
.anode.lv-down .sico { color: var(--stage-muted); }
.anode.bneck .abox { stroke: var(--stage-hot); stroke-width: 2.6; fill: #2a1714; }
.abadge.crit { fill: var(--stage-hot); stroke: none; }
.abadge.crit + .abadge-t, .abadge.crit ~ .abadge-t { fill: #0d1117 !important; font-weight: 700; }
.aedge.bad { stroke: var(--stage-hot); stroke-dasharray: 4 4; opacity: 1; }
.aedge.dead { opacity: .18; }
@media (prefers-reduced-motion: no-preference) {
  .anode.bneck .abox { animation: bneck 1.4s ease-in-out infinite; }
  @keyframes bneck { 50% { filter: drop-shadow(0 0 10px rgba(255, 138, 107, .9)); } }
}

/* Replay */
.rp-tlwrap { padding: 4px 16px 6px; display: grid; gap: 8px; }
.rp-hint { margin: 0; font-size: 13px; color: var(--stage-muted); }
.rp-timeline { display: flex; gap: 6px; overflow-x: auto; padding-bottom: 4px; }
.rp-ev { flex: 0 0 auto; max-width: 220px; display: grid; gap: 3px; text-align: left; padding: 8px 10px; border-radius: 9px; border: 1px solid var(--stage-line); background: var(--stage-2); color: var(--stage-ink); cursor: pointer; font: 500 12.5px/1.3 var(--font-display); border-left-width: 3px; transition: background .2s, border-color .2s; }
.rp-ev:hover { background: var(--stage-3); }
.rp-ev.is-on { background: var(--stage-3); box-shadow: inset 0 0 0 1px var(--stage-accent); }
.rp-ev.base { border-left-color: var(--stage-accent); } .rp-ev.outage { border-left-color: var(--stage-hot); }
.rp-ev.major { border-left-color: #e0785f; } .rp-ev.minor { border-left-color: var(--stage-warm); } .rp-ev.win { border-left-color: var(--stage-good); }
.rp-wk { font: 500 10.5px/1 var(--font-mono); letter-spacing: .06em; text-transform: uppercase; color: var(--stage-muted); }
.rp-t code { font: 500 11px var(--font-mono); }
.rp-play { justify-self: start; border: 1px solid var(--stage-line) !important; color: var(--stage-ink) !important; }
.rp-grid { display: grid; grid-template-columns: minmax(0, 1.05fr) minmax(0, 1fr); gap: 14px; padding: 6px 16px 16px; align-items: start; }
.rp-diag { border: 1px solid var(--stage-line); border-radius: 12px; padding: 8px; background: rgba(0, 0, 0, .15); }
.rp-legend { display: flex; flex-wrap: wrap; gap: 4px 12px; margin: 4px 6px 2px; font-size: 11.5px; color: var(--stage-muted); }
.lg { display: inline-block; width: 10px; height: 10px; border-radius: 3px; margin-right: 5px; vertical-align: -1px; }
.lg.ok { background: var(--stage-good); } .lg.warn { background: var(--stage-warm); } .lg.hot { background: var(--stage-hot); }
.lg.down { border: 1.5px dashed var(--stage-hot); } .lg.bad { height: 3px; background: var(--stage-hot); vertical-align: 2px; }
.rp-detail { color: var(--stage-ink); font-size: 14.5px; line-height: 1.6; max-height: 640px; overflow-y: auto; padding-right: 4px; }
.rp-detail h3 { margin: 4px 0 6px; font-size: 18px; font-weight: 600; letter-spacing: -.01em; }
.rp-detail h4 { margin: 16px 0 6px; font: 600 11px/1.3 var(--font-mono); letter-spacing: .08em; text-transform: uppercase; color: var(--stage-muted); }
.rp-detail p { margin: 0 0 6px; }
.rp-detail a { color: var(--stage-accent); }
.rp-detail code { font: 500 12px var(--font-mono); background: var(--stage-3); padding: 1px 5px; border-radius: 4px; }
.rp-sevline { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; font: 600 10.5px/1.4 var(--font-mono); letter-spacing: .08em; text-transform: uppercase; color: var(--stage-muted); }
.rp-sevline.outage { color: var(--stage-hot); } .rp-sevline.major { color: #e0785f; } .rp-sevline.minor { color: var(--stage-warm); } .rp-sevline.win { color: var(--stage-good); } .rp-sevline.base { color: var(--stage-accent); }
.rp-cause { padding: 8px 10px; border-radius: 8px; background: var(--stage-2); border: 1px solid var(--stage-line); font-size: 13.5px; color: var(--stage-muted); }
.rp-cause b { color: var(--stage-ink); font-weight: 500; }
.rp-mech { margin: 0; padding-left: 0; list-style: none; counter-reset: m; display: grid; gap: 6px; }
.rp-mech li { counter-increment: m; position: relative; padding-left: 30px; }
.rp-mech li::before { content: counter(m); position: absolute; left: 0; top: 1px; width: 20px; height: 20px; border-radius: 6px; display: grid; place-items: center; background: var(--stage-3); font: 600 11px/1 var(--font-mono); color: var(--stage-accent); }
.rp-nums { display: grid; gap: 4px; padding: 10px 12px; border-radius: 8px; background: #0a0e14; border: 1px solid var(--stage-line); font: 500 12.5px/1.6 var(--font-mono); color: var(--stage-ink); }
.rp-fixes { margin: 0; padding: 0; list-style: none; display: grid; gap: 8px; }
.rp-fixes li { display: grid; gap: 6px; padding: 10px 12px; border-radius: 8px; border: 1px solid #2f6b52; background: #11261d; }
.rp-fix { justify-self: start; border: 1px solid var(--stage-good) !important; color: var(--stage-good) !important; background: transparent !important; font-size: 12.5px !important; }
.rp-fix:hover { background: #1b4434 !important; }
.rp-faq { border: 1px solid var(--stage-line); border-radius: 8px; padding: 8px 12px; margin-top: 6px; background: var(--stage-2); }
.rp-faq summary { cursor: pointer; font-weight: 500; }
.rp-faq p { margin: 8px 0 2px; color: var(--stage-muted); }
.rp-rows { display: grid; gap: 6px; }
.rp-row { display: grid; grid-template-columns: 120px minmax(0, 1fr) 70px; gap: 10px; align-items: center; font-size: 13.5px; }
.rp-row b { font: 600 12.5px var(--font-mono); text-align: right; }
.rp-bar { height: 8px; background: var(--stage-3); border-radius: 4px; overflow: hidden; }
.rp-bar i { display: block; height: 100%; border-radius: 4px; }
.rp-parts { margin: 0; padding: 0; list-style: none; display: grid; gap: 4px; }
.rp-parts li { display: flex; justify-content: space-between; gap: 10px; padding: 6px 10px; border-radius: 6px; background: var(--stage-2); font-size: 13.5px; }
.rp-parts b { font: 600 12.5px var(--font-mono); }
.rp-note { font-size: 13px; color: var(--stage-muted); margin-top: 12px !important; }
.rp-wins { margin: 0; padding-left: 18px; display: grid; gap: 8px; }
.arch-final { max-width: 620px; margin: 0 auto; }
@media (prefers-reduced-motion: no-preference) {
  .rp-anim { animation: rpIn .35s cubic-bezier(.2, .7, .2, 1) both; }
  @keyframes rpIn { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: none; } }
}
@media (max-width: 960px) {
  .rp-grid { grid-template-columns: minmax(0, 1fr); }
  .rp-detail { max-height: none; }
}

/* Click-to-enlarge */
.sim .arch-host { position: relative; cursor: zoom-in; }
.sim .arch-host::after { content: "⤢ Click to enlarge"; position: absolute; right: 10px; bottom: 8px; font: 500 11px/1 var(--font-display); color: var(--stage-muted); background: rgba(13, 17, 23, .7); border: 1px solid var(--stage-line); padding: 4px 7px; border-radius: 6px; opacity: 0; transition: opacity .2s; pointer-events: none; }
.sim .arch-host:hover::after { opacity: 1; }
.sim-modal { position: fixed; inset: 0; z-index: 40; display: grid; place-items: center; padding: max(16px, env(safe-area-inset-top, 0px)) max(16px, env(safe-area-inset-right, 0px)) max(16px, env(safe-area-inset-bottom, 0px)) max(16px, env(safe-area-inset-left, 0px)); background: rgba(5, 8, 12, .72); backdrop-filter: blur(4px); }
.sim-modal[hidden] { display: none; }
.sim-modal-box { width: min(1100px, 100%); max-height: 100%; display: flex; flex-direction: column; box-shadow: 0 30px 80px -20px rgba(0, 0, 0, .6); }
.sim-modal-body { flex: 1 1 auto; min-height: 0; overflow: auto; padding: 12px 18px; display: grid; place-items: center; }
.sim-modal-body svg { width: 100%; height: auto; max-height: calc(100vh - 150px); }
.sim-modal-foot { margin: 0; padding: 8px 18px 14px; display: flex; flex-wrap: wrap; gap: 4px 14px; font-size: 12px; color: var(--stage-muted); }
.sim-modal-foot:empty { display: none; }
.sim-modal-x { border: 1px solid var(--stage-line); background: transparent; color: var(--stage-ink); font-size: 20px; line-height: 1; width: 32px; height: 32px; border-radius: 8px; cursor: pointer; }
.sim-modal-x:hover { border-color: var(--stage-accent); }
@media (prefers-reduced-motion: no-preference) {
  .sim-modal:not([hidden]) { animation: fade .18s ease both; }
  .sim-modal:not([hidden]) .sim-modal-box { animation: pop .25s cubic-bezier(.2, .7, .2, 1) both; }
}

/* Architecture diagrams: readable labels that lines never cover */
.arch-svg text { paint-order: stroke; stroke: var(--stage); stroke-width: 5px; stroke-linejoin: round; }
.arch-svg .t-label { font-size: 15px; }
.arch-svg .t-small { font-size: 13px; }
.arch-svg .abadge-t { stroke: none; }
.arch-svg .aq { stroke: none; }
.arch-svg .alabel { font-size: 11.5px !important; }

/* Press feedback, same rule as the rest of the site. */
@media (prefers-reduced-motion: no-preference) {
  .sim-opt, .rp-ev, .sim-step button { transition: border-color .2s, background .2s, scale .15s var(--ease); }
  .sim-opt:active, .rp-ev:active, .sim-step button:active:not(:disabled) { scale: .985; }
  .sim-run:active:not(:disabled), .sim-nav .btn:active, .rp-fix:active { scale: .96; }
}

/* Interview practice: library, workspace and whiteboard. Uses the site's tokens. */
.practice { max-width: 1140px; margin: 0 auto; }
:root { --tier-bad: #c4323a; --wb-edge: var(--accent); --wb-data: var(--good); --wb-async: var(--amber); --wb-ink: #c2410c; --wb-note: #fff7d6; --wb-note-line: #ead98a; --wb-note-ink: #3a3214; }
:root[data-theme="dark"] { --tier-bad: #ff7b7b; --wb-ink: #ff9a6b; --wb-note: #2e2a17; --wb-note-line: #554b22; --wb-note-ink: #f1e6b5; }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) { --tier-bad: #ff7b7b; --wb-ink: #ff9a6b; --wb-note: #2e2a17; --wb-note-line: #554b22; --wb-note-ink: #f1e6b5; } }

/* ---------- Library ---------- */
.pq-head h1 { font-weight: 600; font-size: clamp(30px, 4.6vw, 44px); line-height: 1.08; letter-spacing: -0.035em; margin: 0 0 14px; text-wrap: balance; max-width: 18em; }
.pq-lede { margin: 0 0 20px; font-size: 17px; line-height: 1.6; color: var(--soft-ink); max-width: 44em; }
.pq-how { display: flex; flex-wrap: wrap; align-items: center; gap: 6px 4px; margin: 0 0 14px; font-size: 13px; color: var(--soft-ink); }
.pq-how span { display: inline-flex; align-items: center; gap: 6px; padding: 5px 10px 5px 6px; border: 1px solid var(--line); border-radius: 999px; background: var(--panel); }
.pq-how b { display: grid; place-items: center; width: 18px; height: 18px; border-radius: 50%; background: var(--accent-soft); color: var(--accent); font: 500 10.5px/1 var(--font-mono); }
.pq-how i { width: 10px; height: 1px; background: var(--line); }
.pq-note { margin: 0 0 26px; font-size: 13.5px; color: var(--muted); }
.pq-filters { display: inline-flex; gap: 2px; padding: 3px; margin-bottom: 16px; border: 1px solid var(--line); border-radius: 10px; background: var(--panel); }
.pq-filters button { font: 500 13px/1 var(--font-display); padding: 8px 12px; border: 0; border-radius: 7px; background: none; color: var(--muted); cursor: pointer; }
.pq-filters button[aria-selected="true"] { background: var(--accent-soft); color: var(--accent); }
.pq-grid { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(auto-fill, minmax(258px, 1fr)); gap: 12px; }
.pq-grid > li[hidden] { display: none; }
.pq-card { height: 100%; display: flex; flex-direction: column; gap: 8px; padding: 16px 16px 14px; border: 1px solid var(--line); border-radius: 13px; background: var(--panel); color: var(--ink); text-decoration: none; transition: border-color .2s, box-shadow .2s; }
a.pq-card:hover { border-color: color-mix(in srgb, var(--accent) 50%, var(--line)); box-shadow: 0 10px 28px -18px color-mix(in srgb, var(--accent) 60%, transparent); }
.pq-card.is-soon { opacity: .62; }
.pq-card h2 { margin: 2px 0 0; font-size: 17px; font-weight: 600; letter-spacing: -0.015em; }
.pq-card p { margin: 0; font-size: 14px; line-height: 1.5; color: var(--muted); }
.pq-card-top { display: flex; justify-content: space-between; align-items: center; }
.pq-mins { font: 500 11.5px/1 var(--font-mono); color: var(--muted); }
.pq-level { display: inline-block; font: 500 10.5px/1 var(--font-mono); letter-spacing: .06em; text-transform: uppercase; padding: 4px 7px; border-radius: 5px; }
.l-easy { background: color-mix(in srgb, var(--good) 14%, transparent); color: var(--good); }
.l-medium { background: var(--accent-soft); color: var(--accent); }
.l-hard { background: var(--amber-soft); color: var(--amber); }
.pq-tags { display: flex; flex-wrap: wrap; gap: 5px; margin-top: auto; padding-top: 4px; }
.pq-tags span { font: 400 11.5px/1 var(--font-mono); padding: 4px 6px; border-radius: 5px; background: var(--code-bg); color: var(--soft-ink); }
.pq-prog { display: flex; align-items: center; gap: 10px; padding-top: 10px; margin-top: 4px; border-top: 1px solid var(--line); font-size: 12.5px; color: var(--muted); }
.pq-prog.soon span { font: 500 11px/1 var(--font-mono); letter-spacing: .05em; text-transform: uppercase; }
.pq-bar { flex: 1; height: 5px; border-radius: 3px; background: var(--code-bg); overflow: hidden; }
.pq-bar i { display: block; height: 100%; border-radius: 3px; background: var(--accent); transition: width .5s var(--ease); }

/* ---------- Workspace ---------- */
.pw-head { display: flex; flex-wrap: wrap; justify-content: space-between; align-items: flex-end; gap: 14px 24px; margin-bottom: 16px; }
.pw-head .eyebrow { display: flex; align-items: center; gap: 10px; }
.pw-head h1 { margin: 0; font-weight: 600; font-size: clamp(30px, 4.4vw, 42px); line-height: 1.05; letter-spacing: -0.035em; }
.pw-mode { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; }
.pw-seg { display: inline-flex; gap: 2px; padding: 3px; border: 1px solid var(--line); border-radius: 10px; background: var(--panel); }
.pw-seg button { font: 500 13px/1 var(--font-display); padding: 8px 12px; border: 0; border-radius: 7px; background: none; color: var(--muted); cursor: pointer; }
.pw-seg button[aria-checked="true"] { background: var(--ink); color: var(--paper); }
.pw-timer { display: inline-flex; align-items: center; gap: 8px; padding: 4px 4px 4px 12px; border: 1px solid var(--line); border-radius: 10px; background: var(--panel); }
.pw-timer[hidden] { display: none; }
.pw-clock { font: 500 16px/1 var(--font-mono); font-variant-numeric: tabular-nums; min-width: 3.4em; }
.pw-clock.over { color: var(--amber); }
.pw-tbtn { font: 500 12.5px/1 var(--font-display); padding: 7px 10px; border-radius: 7px; border: 1px solid var(--line); background: var(--paper); color: var(--ink); cursor: pointer; }
.pw-prompt { padding: 16px 20px; border-radius: 13px; border: 1px solid var(--line); border-left: 3px solid var(--accent); background: var(--panel); font-size: 16.5px; line-height: 1.6; }
.pw-prompt p { margin: 0 0 8px; }
.pw-prompt p:last-child { margin-bottom: 0; }
.pw-ask { font: 500 11px/1.4 var(--font-mono) !important; letter-spacing: .08em; text-transform: uppercase; color: var(--muted); }
.pw-lessons { display: flex; flex-wrap: wrap; align-items: center; gap: 6px; margin: 12px 0 0; font-size: 13px; color: var(--muted); }
.pw-lessons > span { margin-right: 4px; }
.pq-lesson { display: inline-flex; gap: 6px; align-items: center; padding: 4px 9px 4px 5px; border: 1px solid var(--line); border-radius: 999px; background: var(--panel); text-decoration: none; color: var(--soft-ink); font-size: 12.5px; }
.pq-lesson span { font: 500 10.5px/1 var(--font-mono); padding: 3px 5px; border-radius: 999px; background: var(--accent-soft); color: var(--accent); }
.pq-lesson:hover { border-color: color-mix(in srgb, var(--accent) 50%, var(--line)); color: var(--ink); }

.pw-stages { list-style: none; margin: 22px 0 14px; padding: 0; display: grid; grid-template-columns: repeat(var(--n, 7), minmax(0, 1fr)); gap: 6px; }
.pw-stages button { width: 100%; height: 100%; display: flex; align-items: center; gap: 8px; text-align: left; padding: 9px 9px; min-width: 0; border-radius: 10px; border: 1px solid var(--line); background: var(--panel); color: var(--soft-ink); font: 500 13px/1.25 var(--font-display); cursor: pointer; transition: border-color .2s, background .2s; }
.pw-stages button:hover { border-color: color-mix(in srgb, var(--accent) 45%, var(--line)); }
.pw-stages small { display: block; font: 400 11px/1.3 var(--font-mono); color: var(--muted); }
.pw-n { flex: none; display: grid; place-items: center; width: 22px; height: 22px; border-radius: 50%; background: var(--code-bg); font: 500 11px/1 var(--font-mono); color: var(--muted); }
.pw-stages .is-done .pw-n { background: color-mix(in srgb, var(--good) 16%, transparent); color: var(--good); }
.pw-stages .is-cur button { border-color: var(--accent); background: var(--accent-soft); color: var(--ink); }
.pw-stages .is-cur .pw-n { background: var(--accent); color: var(--panel); }
.pw-stages .is-late button { border-color: color-mix(in srgb, var(--amber) 55%, var(--line)); }

.pw-panel { padding: 20px 22px 22px; border: 1px solid var(--line); border-radius: 14px; background: var(--panel); }
.pw-ph { display: flex; flex-wrap: wrap; justify-content: space-between; align-items: baseline; gap: 6px 16px; margin-bottom: 6px; }
.pw-ph h2 { margin: 0; font-size: 21px; font-weight: 600; letter-spacing: -0.02em; }
.pw-ph h2 span { display: block; font: 500 11px/1.6 var(--font-mono); letter-spacing: .08em; text-transform: uppercase; color: var(--muted); }
.pw-budget { font: 400 12px/1 var(--font-mono); color: var(--muted); }
.pw-intro { margin: 0 0 14px; color: var(--soft-ink); font-size: 15.5px; line-height: 1.6; max-width: 52em; }
.pw-tip { margin: 10px 0 0; font-size: 13.5px; color: var(--muted); }
.pw-sub { margin: 20px 0 8px; font-size: 15px; font-weight: 600; }
.pw-text { width: 100%; display: block; resize: vertical; padding: 12px 14px; border: 1px solid var(--line); border-radius: 10px; background: var(--paper); color: var(--ink); font: 400 15px/1.55 var(--font-display); }
.pw-text.mono { font: 400 13.5px/1.6 var(--font-mono); }
.pw-text:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 18%, transparent); }
.pw-cols { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 18px; }
.pw-cols h3, .pw-walk h3 { margin: 0 0 8px; font-size: 14px; font-weight: 600; }

.pw-list ul { list-style: none; margin: 0 0 8px; padding: 0; display: grid; gap: 5px; }
.pw-list li { display: flex; justify-content: space-between; align-items: center; gap: 8px; padding: 8px 8px 8px 12px; border: 1px solid var(--line); border-radius: 9px; background: var(--paper); font-size: 14.5px; }
.pw-list li.pw-none { color: var(--muted); border-style: dashed; background: none; }
.pw-list li button { flex: none; width: 24px; height: 24px; border: 0; border-radius: 6px; background: none; color: var(--muted); font-size: 16px; cursor: pointer; }
.pw-list li button:hover { background: var(--code-bg); color: var(--ink); }
.pw-add { display: flex; gap: 6px; }
.pw-add input { flex: 1; min-width: 0; padding: 9px 12px; border: 1px solid var(--line); border-radius: 9px; background: var(--paper); color: var(--ink); font: 400 14.5px var(--font-display); }
.pw-add input:focus { outline: none; border-color: var(--accent); }
.pw-add button, .pw-chips button, .pw-show, .wb-txt, .pw-tabs button { font: 500 13px/1 var(--font-display); padding: 9px 12px; border-radius: 9px; border: 1px solid var(--line); background: var(--panel); color: var(--ink); cursor: pointer; }
.pw-chips { display: flex; flex-wrap: wrap; gap: 5px; margin-top: 8px; }
.pw-chips button { padding: 6px 9px; font-size: 12.5px; color: var(--soft-ink); border-style: dashed; }
.pw-chips button:hover, .pw-add button:hover, .wb-txt:hover { border-color: color-mix(in srgb, var(--accent) 50%, var(--line)); color: var(--accent); }

.pw-reveal { margin-top: 18px; padding-top: 16px; border-top: 1px dashed var(--line); display: flex; flex-wrap: wrap; align-items: center; gap: 10px 14px; }
.pw-reveal.is-open { display: block; border-top-style: solid; animation: pwIn .35s var(--ease); }
@keyframes pwIn { from { opacity: 0; transform: translateY(6px); } }
.pw-show { background: var(--accent-soft); color: var(--accent); border-color: transparent; }
.pw-show:hover { border-color: var(--accent); }
.pw-hint { font-size: 13px; color: var(--muted); }
.pw-lock { margin: 0; padding: 10px 14px; border-radius: 10px; background: var(--amber-soft); color: var(--amber); font-size: 14px; }
.pw-score { margin: 0 0 12px; font-size: 14.5px; color: var(--soft-ink); }
.pw-score b { font-weight: 600; color: var(--ink); }
.pw-qa, .pw-ref { list-style: none; margin: 0; padding: 0; display: grid; gap: 8px; }
.pw-qa li, .pw-ref li { padding: 11px 14px; border: 1px solid var(--line); border-radius: 10px; background: var(--paper); }
.pw-qa-q, .pw-ref li > div { display: flex; flex-wrap: wrap; align-items: baseline; gap: 4px 10px; font-weight: 500; font-size: 15px; }
.pw-qa-a { margin: 6px 0 0; font-size: 14.5px; line-height: 1.55; color: var(--soft-ink); }
.pw-qa-a span { font: 500 10.5px/1 var(--font-mono); letter-spacing: .06em; text-transform: uppercase; color: var(--accent); margin-right: 8px; }
.pw-why { margin: 5px 0 0; font-size: 13.5px; line-height: 1.55; color: var(--muted); }
.pw-st { margin-left: auto; font: 500 11px/1.4 var(--font-mono); white-space: nowrap; }
.pw-st.ok { color: var(--good); }
.pw-st.miss { color: var(--amber); }
.pw-tier { font: 500 10px/1 var(--font-mono); letter-spacing: .06em; text-transform: uppercase; padding: 3px 6px; border-radius: 4px; background: var(--accent-soft); color: var(--accent); }
.t-nice .pw-tier { background: var(--code-bg); color: var(--soft-ink); }
.t-out .pw-tier { background: var(--amber-soft); color: var(--amber); }
.t-out { opacity: .85; }
.pw-reveal p, .pw-reveal li { line-height: 1.6; }
.pw-reveal > p, .pw-reveal > ul:not(.pw-qa), .pw-reveal .pw-cols p, .pw-reveal .pw-cols > div > ul:not(.pw-ref) { font-size: 15px; color: var(--soft-ink); max-width: 52em; }
.pw-reveal code, .pw-prompt code, .pw-why code, .pw-intro code, .pw-rubric code, .pw-mist code, .pw-walk code, .pw-qa code, .pw-ref code { font: 500 .86em var(--font-mono); padding: 1px 5px; border-radius: 4px; background: var(--code-bg); }
.pq-code { margin: 10px 0; padding: 12px 14px; border-radius: 10px; background: var(--code-bg); overflow-x: auto; font: 400 13px/1.6 var(--font-mono); color: var(--ink); }
.pq-code code { background: none; padding: 0; font: inherit; }

.pw-est { display: grid; grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.1fr); gap: 18px; align-items: start; }
.pw-inputs { display: grid; gap: 8px; }
.pw-in { display: grid; gap: 5px; font-size: 13.5px; color: var(--soft-ink); }
.pw-inbox { display: flex; align-items: center; border: 1px solid var(--line); border-radius: 9px; background: var(--paper); }
.pw-inbox:focus-within { border-color: var(--accent); }
.pw-inbox input { flex: 1; min-width: 0; padding: 9px 12px; border: 0; background: none; color: var(--ink); font: 500 14.5px var(--font-mono); }
.pw-inbox input:focus { outline: none; }
.pw-inbox em { font-style: normal; padding-right: 12px; font: 400 12px var(--font-mono); color: var(--muted); white-space: nowrap; }
.pw-link { justify-self: start; border: 0; padding: 4px 0; background: none; color: var(--accent); font: 500 13px var(--font-display); cursor: pointer; }
.pw-out { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 8px; }
.pw-res { padding: 11px 13px; border-radius: 10px; background: var(--stage, #0e1218); border: 1px solid var(--stage-line, #2b3341); color: var(--stage-ink, #e9edf2); }
.pw-res span { display: block; font-size: 12px; color: var(--stage-muted, #8c96a5); }
.pw-res b { display: block; margin-top: 4px; font: 600 19px/1.15 var(--font-mono); color: var(--stage-accent, #8ea8ff); font-variant-numeric: tabular-nums; }
.pw-res small { display: block; margin-top: 4px; font-size: 12px; line-height: 1.45; color: var(--stage-muted, #8c96a5); }

.pw-tabs { display: inline-flex; gap: 2px; padding: 3px; margin-bottom: 10px; border: 1px solid var(--line); border-radius: 10px; background: var(--paper); }
.pw-tabs button { border: 0; background: none; color: var(--muted); padding: 8px 12px; border-radius: 7px; }
.pw-tabs button[aria-selected="true"] { background: var(--panel); color: var(--ink); box-shadow: 0 1px 2px rgba(0, 0, 0, .08); }
.pw-refwrap .pw-reveal { margin-top: 0; padding-top: 0; border-top: 0; }
.pw-keys { margin: 10px 0 0; font-size: 12.5px; color: var(--muted); line-height: 2; }
.pw-keys kbd { margin: 0 2px 0 6px; }
.pw-walk { margin-top: 16px; }
.pw-walk ol { margin: 0; padding-left: 22px; display: grid; gap: 6px; font-size: 14.5px; color: var(--soft-ink); }

.pw-dive { border: 1px solid var(--line); border-radius: 11px; background: var(--paper); margin-top: 8px; }
.pw-dive summary { list-style: none; display: flex; align-items: baseline; gap: 10px; padding: 13px 14px; cursor: pointer; font-weight: 500; font-size: 15px; }
.pw-dive summary::-webkit-details-marker { display: none; }
.pw-dn { flex: none; display: grid; place-items: center; width: 22px; height: 22px; border-radius: 50%; background: var(--accent-soft); color: var(--accent); font: 500 11px/1 var(--font-mono); transform: translateY(2px); }
.pw-dst { margin-left: auto; font: 400 11px/1 var(--font-mono); color: var(--good); white-space: nowrap; }
.pw-dbody { padding: 0 14px 14px 46px; }
.pw-dbody .pw-why { margin: 0 0 8px; }
.pw-dbody .pw-text { background: var(--panel); }

.pw-time { margin: 0 0 12px; font-size: 15px; }
.pw-time b { font: 600 15px var(--font-mono); }
.pw-rscore { display: flex; align-items: center; gap: 12px; margin-bottom: 10px; font-size: 14px; color: var(--soft-ink); }
.pw-rscore .pq-bar { max-width: 260px; height: 7px; }
.pw-rubric { list-style: none; margin: 0; padding: 0; display: grid; gap: 5px; }
.pw-rubric label { display: flex; gap: 10px; align-items: flex-start; padding: 10px 12px; border: 1px solid var(--line); border-radius: 9px; background: var(--paper); cursor: pointer; font-size: 14.5px; line-height: 1.5; }
.pw-rubric input { margin-top: 4px; accent-color: var(--accent); }
.pw-mist { margin: 0; padding-left: 20px; display: grid; gap: 6px; font-size: 14.5px; color: var(--soft-ink); line-height: 1.55; }
.pw-acts { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 22px; }
.pw-acts .btn, .pw-nav .btn { border: 0; cursor: pointer; }
.pw-acts .btn-ghost, .pw-nav .btn-ghost { border: 1px solid var(--line); }
.pw-next { display: grid; gap: 2px; margin-top: 18px; padding: 14px 16px; border-radius: 12px; border: 1px solid var(--line); text-decoration: none; color: var(--ink); font-weight: 500; }
.pw-next span { font: 500 11px/1.4 var(--font-mono); letter-spacing: .08em; text-transform: uppercase; color: var(--muted); }
.pw-next:hover { border-color: var(--accent); }
.pw-nav { display: flex; justify-content: space-between; gap: 10px; margin-top: 14px; }
.pw-nav .btn:disabled { opacity: .4; cursor: not-allowed; }
.pw-nav .btn[hidden] { display: none; }

/* ---------- Whiteboard ---------- */
.wb { border: 1px solid var(--line); border-radius: 13px; background: var(--paper); overflow: hidden; }
.wb.is-full { position: fixed; inset: 0; z-index: 40; border-radius: 0; display: flex; flex-direction: column; }
body.wb-locked { overflow: hidden; }
.wb-bar { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; padding: 7px 8px; border-bottom: 1px solid var(--line); background: var(--panel); }
.wb-group { display: flex; gap: 2px; align-items: center; }
.wb-group + .wb-group { padding-left: 8px; border-left: 1px solid var(--line); }
.wb-right { margin-left: auto; gap: 6px; }
.wb-tool { position: relative; display: grid; place-items: center; width: 34px; height: 34px; border: 1px solid transparent; border-radius: 8px; background: none; color: var(--soft-ink); cursor: pointer; }
.wb-tool:hover { background: var(--paper); color: var(--ink); }
.wb-tool.on { background: var(--accent-soft); color: var(--accent); border-color: color-mix(in srgb, var(--accent) 35%, transparent); }
.wb-tool:disabled { opacity: .35; cursor: default; background: none; }
.wb-tool kbd { position: absolute; right: 1px; bottom: 1px; min-width: 0; height: auto; padding: 0 2px; border: 0; background: none; font-size: 8.5px; line-height: 1; color: var(--muted); }
.wb-ti { width: 17px; height: 17px; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
.wb-txt { padding: 8px 10px; font-size: 12.5px; }
.wb-body { display: grid; grid-template-columns: 168px minmax(0, 1fr); height: 600px; }
.is-ro .wb-body { grid-template-columns: minmax(0, 1fr); height: 520px; }
.wb.is-full .wb-body { flex: 1; height: auto; }
.wb-parts { display: flex; flex-direction: column; gap: 2px; padding: 8px 6px; border-right: 1px solid var(--line); background: var(--panel); overflow-y: auto; }
.wb-part { display: flex; align-items: center; gap: 8px; padding: 6px 8px; border: 0; border-radius: 8px; background: none; color: var(--soft-ink); font: 500 13px/1.2 var(--font-display); text-align: left; cursor: grab; touch-action: none; user-select: none; }
.wb-part:hover { background: var(--paper); color: var(--ink); }
.wb-phead { margin: 8px 8px 4px; font: 500 10.5px/1.2 var(--font-mono); letter-spacing: .08em; text-transform: uppercase; color: var(--muted); }
.wb-phead:first-child { margin-top: 2px; }
.wb-rel { display: flex; align-items: center; gap: 8px; padding: 6px 8px; border: 1px solid transparent; border-radius: 8px; background: none; color: var(--soft-ink); font: 500 13px/1.2 var(--font-display); text-align: left; cursor: pointer; }
.wb-rel:hover { background: var(--paper); color: var(--ink); }
.wb-rel.on { border-color: color-mix(in srgb, var(--accent) 55%, var(--line)); background: var(--accent-soft); color: var(--ink); }
.wb-rel .wb-rchip { width: 40px; background: var(--code-bg); }
.wb-rel .wb-rchip svg { width: 32px; height: 20px; }
.wb-rel .wb-rchip svg { stroke: var(--soft-ink); stroke-width: 1.6; }
.wb-rchip svg .f { fill: var(--soft-ink); }
.wb-rel.on .wb-rchip svg { stroke: var(--accent); } .wb-rel.on .wb-rchip svg .f { fill: var(--accent); }
.wb-part.k-interface .wb-pchip { background: color-mix(in srgb, var(--good) 14%, transparent); } .wb-part.k-interface svg { stroke: var(--wb-data); }
.wb-part.k-enum .wb-pchip { background: var(--amber-soft); } .wb-part.k-enum svg { stroke: var(--wb-async); }
.wb-unode text { pointer-events: none; }
.wb-uedge.is-sel .wb-line, .wb-uedge:hover .wb-line { stroke: var(--accent); }
.wb-uedit { position: absolute; z-index: 4; width: 300px; display: grid; gap: 9px; padding: 12px; border: 1px solid color-mix(in srgb, var(--accent) 50%, var(--line)); border-radius: 11px; background: var(--panel); box-shadow: 0 14px 34px -14px rgba(0, 0, 0, .45); }
.wb-uedit label { display: grid; gap: 4px; }
.wb-uedit label span { font: 500 11px/1.2 var(--font-mono); letter-spacing: .04em; color: var(--muted); }
.wb-uedit input, .wb-uedit textarea { width: 100%; box-sizing: border-box; padding: 7px 9px; border: 1px solid var(--line); border-radius: 7px; background: var(--paper); color: var(--ink); font: 400 12.5px/1.5 var(--font-mono); resize: vertical; }
.wb-uedit input { font: 600 13.5px/1.3 var(--font-display); }
.wb-uedit input:focus, .wb-uedit textarea:focus { outline: none; border-color: var(--accent); }
.wb-uedit-f { display: flex; align-items: center; justify-content: space-between; gap: 8px; }
.wb-uedit-f small { color: var(--muted); font-size: 11.5px; }
.wb-uedit-f kbd { font-size: 10.5px; }
.wb-uedit-f button { padding: 6px 14px; border: 0; border-radius: 7px; background: var(--accent); color: var(--panel); font: 500 12.5px/1 var(--font-display); cursor: pointer; }
.wb-ctx select { padding: 5px 6px; border: 1px solid var(--line); border-radius: 6px; background: var(--paper); color: var(--ink); font: 500 12.5px/1 var(--font-display); }
.wb-pchip { flex: none; display: grid; place-items: center; width: 26px; height: 26px; border-radius: 7px; background: var(--accent-soft); }
.wb-pchip svg { width: 15px; height: 15px; fill: none; stroke: var(--wb-edge); stroke-width: 1.9; stroke-linecap: round; stroke-linejoin: round; }
.wb-part.k-data .wb-pchip { background: color-mix(in srgb, var(--good) 14%, transparent); } .wb-part.k-data svg { stroke: var(--wb-data); }
.wb-part.k-async .wb-pchip { background: var(--amber-soft); } .wb-part.k-async svg { stroke: var(--wb-async); }
.wb-part.k-plain .wb-pchip { background: var(--code-bg); } .wb-part.k-plain svg { stroke: var(--muted); }
.wb-ghostpart { position: fixed; z-index: 50; pointer-events: none; transform: translate(-50%, -50%); padding: 10px 14px; border-radius: 10px; border: 1.5px solid var(--accent); background: var(--panel); font: 500 13px var(--font-display); color: var(--ink); box-shadow: 0 10px 30px -10px rgba(0, 0, 0, .35); }

.wb-canvas { position: relative; overflow: hidden; outline: none; touch-action: none; cursor: default; user-select: none; -webkit-user-select: none; }
.wb-canvas:focus-visible { box-shadow: inset 0 0 0 2px color-mix(in srgb, var(--accent) 45%, transparent); }
.wb-canvas[data-tool="pen"] { cursor: crosshair; }
.wb-canvas[data-tool="text"] { cursor: text; }
.wb-canvas[data-tool="link"] .wb-node, .wb-port { cursor: crosshair; }
.wb-canvas[data-tool="erase"] { cursor: cell; }
.wb-canvas.is-panning, .is-ro .wb-canvas { cursor: grab; }
.wb-svg { display: block; width: 100%; height: 100%; }
.wb-dot { fill: color-mix(in srgb, var(--muted) 40%, transparent); }
.wb-grid { pointer-events: none; }
.wb-node { cursor: move; }
.is-ro .wb-node { cursor: inherit; }
.wb-box { fill: var(--panel); stroke: color-mix(in srgb, var(--ink) 70%, var(--line)); stroke-width: 1.3; transition: stroke .15s; }
.wb-chip { fill: var(--accent-soft); }
.wb-ico { fill: none; stroke: var(--wb-edge); stroke-width: 1.9; stroke-linecap: round; stroke-linejoin: round; pointer-events: none; }
.k-data .wb-chip { fill: color-mix(in srgb, var(--good) 14%, var(--panel)); } .k-data .wb-ico { stroke: var(--wb-data); }
.k-async .wb-chip { fill: var(--amber-soft); } .k-async .wb-ico { stroke: var(--wb-async); }
.k-plain .wb-chip { fill: var(--code-bg); } .k-plain .wb-ico { stroke: var(--muted); }
.wb-label { font: 500 13.5px var(--font-display); fill: var(--ink); pointer-events: none; }
.wb-sub { font: 400 11.5px var(--font-display); fill: var(--muted); pointer-events: none; }
.wb-node.is-sel .wb-box { stroke: var(--accent); stroke-width: 2; }
.wb-node:hover .wb-box { stroke: var(--accent); }
.wb-port { fill: var(--panel); stroke: var(--accent); stroke-width: 1.8; }
.wb-port:hover { fill: var(--accent); }
.wb-hit { fill: none; stroke: transparent; stroke-width: 14; stroke-linecap: round; }
.wb-line { fill: none; stroke: color-mix(in srgb, var(--soft-ink) 80%, var(--line)); stroke-width: 1.6; pointer-events: none; }
.wb-edge { cursor: pointer; }
.wb-edge.dashed .wb-line { stroke-dasharray: 6 5; }
.wb-edge.is-sel .wb-line, .wb-edge:hover .wb-line { stroke: var(--accent); stroke-width: 2; }
.wb-arrowhead { fill: color-mix(in srgb, var(--soft-ink) 80%, var(--line)); }
.wb-arrowhead.sel { fill: var(--accent); }
.wb-ghost { stroke: var(--accent); stroke-dasharray: 4 4; }
.wb-target { fill: none; stroke: var(--accent); stroke-width: 1.5; stroke-dasharray: 4 3; }
.wb-elab-g { cursor: pointer; }
.wb-elab-bg { fill: var(--panel); stroke: var(--line); }
.wb-elab-g.is-sel .wb-elab-bg { stroke: var(--accent); }
.wb-elab { font: 400 11.5px var(--font-mono); fill: var(--soft-ink); pointer-events: none; }
.wb-ink { fill: none; stroke: var(--wb-ink); stroke-width: 2.4; stroke-linecap: round; stroke-linejoin: round; pointer-events: none; }
.wb-stroke { cursor: pointer; }
.wb-stroke.is-sel .wb-ink { stroke-width: 3.6; }
.wb-note { cursor: move; }
.wb-note-bg { fill: var(--wb-note); stroke: var(--wb-note-line); }
.wb-note.is-sel .wb-note-bg { stroke: var(--accent); stroke-width: 1.6; }
.wb-note-t { font: 400 13.5px var(--font-display); fill: var(--wb-note-ink); pointer-events: none; }
.wb-zoom { position: absolute; right: 10px; bottom: 10px; display: flex; align-items: center; gap: 2px; padding: 3px; border: 1px solid var(--line); border-radius: 9px; background: var(--panel); box-shadow: 0 4px 14px -8px rgba(0, 0, 0, .25); }
.wb-zoom button { min-width: 28px; height: 28px; padding: 0 8px; border: 0; border-radius: 6px; background: none; color: var(--soft-ink); font: 500 14px/1 var(--font-display); cursor: pointer; }
.wb-zoom button:hover { background: var(--paper); color: var(--ink); }
.wb-pct { min-width: 40px; text-align: center; font: 400 11.5px var(--font-mono); color: var(--muted); }
.wb-ctx { position: absolute; z-index: 3; display: flex; gap: 2px; padding: 3px; border: 1px solid var(--line); border-radius: 9px; background: var(--panel); box-shadow: 0 8px 22px -10px rgba(0, 0, 0, .3); white-space: nowrap; }
.wb-ctx[hidden] { display: none; }
.wb-ctx button { padding: 6px 9px; border: 0; border-radius: 6px; background: none; color: var(--soft-ink); font: 500 12.5px/1 var(--font-display); cursor: pointer; }
.wb-ctx button:hover { background: var(--paper); color: var(--ink); }
.wb-ctx button[data-ctx="del"]:hover { color: var(--amber); }
.wb-edit { position: absolute; z-index: 4; padding: 7px 10px; border: 1.5px solid var(--accent); border-radius: 8px; background: var(--panel); color: var(--ink); font: 500 13.5px/1.4 var(--font-display); text-align: center; box-shadow: 0 8px 24px -10px rgba(0, 0, 0, .35); resize: none; }
textarea.wb-edit { text-align: left; font-weight: 400; }
.wb-edit:focus { outline: none; }
.wb-empty { position: absolute; left: 50%; top: 44%; transform: translate(-50%, -50%); width: min(360px, 80%); margin: 0; text-align: center; font-size: 14px; line-height: 1.6; color: var(--muted); pointer-events: none; }
.wb-empty[hidden] { display: none; }

@media (prefers-reduced-motion: no-preference) {
  .pq-filters button, .pw-seg button, .pw-stages button, .pw-show, .pw-add button, .pw-chips button, .wb-tool, .wb-part, .wb-zoom button, .wb-ctx button, .pw-tabs button, .pq-card {
    transition: border-color .2s, background .2s, color .2s, box-shadow .2s, scale .15s var(--ease);
  }
  .pq-filters button:active, .pw-seg button:active, .pw-show:active, .pw-add button:active, .pw-chips button:active, .wb-tool:active:not(:disabled), .wb-zoom button:active, .wb-ctx button:active, .pw-tabs button:active, .pw-tbtn:active, .wb-txt:active { scale: .96; }
  .pw-stages button:active, a.pq-card:active { scale: .985; }
}
@media (prefers-reduced-motion: reduce) { .pw-reveal.is-open { animation: none; } }

@media (max-width: 900px) {
  .pw-stages { grid-template-columns: repeat(4, minmax(0, 1fr)); }
}
@media (max-width: 720px) {
  .pw-cols, .pw-est { grid-template-columns: minmax(0, 1fr); }
  .pw-stages { display: flex; overflow-x: auto; scrollbar-width: none; margin-inline: -16px; padding-inline: 16px; }
  .pw-stages li { flex: none; }
  .pw-stages small { display: none; }
  .pw-panel { padding: 16px 14px 18px; }
  .wb-body { grid-template-columns: minmax(0, 1fr); grid-template-rows: auto minmax(0, 1fr); height: 540px; }
  .wb-parts { flex-direction: row; overflow-x: auto; border-right: 0; border-bottom: 1px solid var(--line); padding: 6px; }
  .wb-part, .wb-rel { flex: none; touch-action: pan-x; }
  .wb-phead { align-self: center; margin: 0 4px; }
  .wb-rel > span:last-child { white-space: nowrap; }
  .wb-part > span:last-child { white-space: nowrap; }
  .wb-tool kbd { display: none; }
  .pw-dbody { padding-left: 14px; }
  .pw-keys { display: none; }
}

/* ---------- Walkthrough articles ----------
   Prose sits on a ~70-character measure; diagrams, tables and code break out to the full column.
   One tint marks the candidate's voice; everything else is type, space and hairlines. */
.pq-crumbs { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; margin: 0 0 18px; font-size: 13.5px; color: var(--muted); }
.pq-crumbs a { color: var(--muted); text-decoration: none; }
.pq-crumbs span:last-child { color: var(--soft-ink); }
.pw-views { display: flex; gap: 24px; margin: 4px 0 28px; border-bottom: 1px solid var(--line); }
.pw-views a { margin-bottom: -1px; padding: 10px 1px 11px; border-bottom: 2px solid transparent; font: 500 14px/1 var(--font-display); color: var(--muted); text-decoration: none; transition: color .15s, border-color .15s; }
.pw-views a[aria-current="page"] { color: var(--ink); border-bottom-color: var(--accent); }

.pa-head { display: block; margin-bottom: 18px; }
.pa-head h1 { margin: 0; font-size: clamp(30px, 4.2vw, 44px); line-height: 1.08; letter-spacing: -0.03em; max-width: 19em; text-wrap: balance; }
.pa-lede { margin: 16px 0 0; max-width: 36em; font-size: 18.5px; line-height: 1.6; color: var(--soft-ink); text-wrap: pretty; }
.pa-meta { display: flex; flex-wrap: wrap; gap: 6px 18px; margin: 16px 0 0; font: 400 12.5px/1.4 var(--font-mono); color: var(--muted); }
.pa-meta span + span::before { content: "·"; margin-right: 18px; color: var(--line); }

.pa-body { min-width: 0; font-family: var(--font-read); font-size: var(--read-size); line-height: 1.7; color: var(--soft-ink); }
.pa-body p, .pa-body li { text-wrap: pretty; }
.pa-body p, .pa-body ul, .pa-body ol { margin: 0 0 1em; }
.pa-body ul, .pa-body ol { padding-inline-start: 1.25em; }
.pa-body li { margin: .35em 0; }
.pa-body li::marker { color: var(--muted); }
.pa-body em { color: var(--ink); }
.pa-body a { color: var(--accent); text-decoration-thickness: from-font; text-underline-offset: 3px; }
.pa-body code { font: 500 .84em var(--font-mono); padding: 1px 5px; border-radius: 4px; background: var(--code-bg); color: var(--ink); overflow-wrap: anywhere; }
.pa-body h2 { margin: 2.6em 0 .7em; font-family: var(--font-display); font-size: 1.65em; font-weight: 600; line-height: 1.2; letter-spacing: -0.02em; color: var(--ink); text-wrap: balance; scroll-margin-top: 28px; }
.pa-body h3 { margin: 2em 0 .5em; font-family: var(--font-display); font-size: 1.18em; font-weight: 600; line-height: 1.3; letter-spacing: -0.01em; color: var(--ink); scroll-margin-top: 28px; }
.pa-body h4 { margin: 1.8em 0 .5em; font-family: var(--font-display); font-size: 1.04em; font-weight: 600; line-height: 1.35; color: var(--ink); scroll-margin-top: 28px; }
.pa-kick { display: block; margin-bottom: 10px; font: 500 11.5px/1.2 var(--font-mono); letter-spacing: .08em; text-transform: uppercase; color: var(--accent); }

/* The short version and the 45-minute strip */
.pa-spoil { display: flex; gap: 10px; align-items: baseline; margin: 0 0 22px; font-family: var(--font-display); font-size: 14px; line-height: 1.5; color: var(--amber); }
.pa-spoil > .pa-spoil-i { flex: none; display: grid; place-items: center; width: 18px; height: 18px; border-radius: 50%; background: var(--amber-soft); font: 600 11px/1 var(--font-mono); transform: translateY(3px); }
.pa-spoil a { color: inherit; }
.pa-sum { margin: 0 0 28px; padding: 18px 22px 8px; border: 1px solid var(--line); border-radius: 14px; background: var(--panel); font-family: var(--font-display); }
.pa-sum-h, .pa-time-h { margin: 0 0 10px; font: 500 11.5px/1.3 var(--font-mono); letter-spacing: .08em; text-transform: uppercase; color: var(--muted); }
.pa-sum ul { list-style: none; margin: 0; padding: 0; counter-reset: sum; }
.pa-sum li { position: relative; margin: 0 0 12px; padding-inline-start: 30px; font-size: 15.5px; line-height: 1.55; color: var(--ink); counter-increment: sum; }
.pa-sum li::before { content: counter(sum); position: absolute; inset-inline-start: 0; top: 1px; display: grid; place-items: center; width: 20px; height: 20px; border-radius: 50%; background: var(--accent-soft); color: var(--accent); font: 500 11px/1 var(--font-mono); }
.pa-time { margin: 0 0 8px; font-family: var(--font-display); }
.pa-time ol { list-style: none; display: flex; gap: 4px; margin: 0; padding: 0; }
.pa-time li { min-width: 0; flex-basis: 0; }
.pa-time button { width: 100%; height: 100%; display: grid; gap: 3px; padding: 10px 2px 2px; border: 0; border-top: 3px solid var(--line); background: none; text-align: start; cursor: pointer; color: var(--soft-ink); transition: border-color .2s, color .2s; }
.pa-time button.on { border-top-color: var(--accent); color: var(--ink); }
.pa-time-t { font-size: 13.5px; font-weight: 500; line-height: 1.25; text-wrap: balance; }
.pa-time-m { font: 400 11px/1.3 var(--font-mono); color: var(--muted); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.pa-time-m { font-variant-numeric: tabular-nums; }

/* Dialogue: a chat window. The interviewer on the left, you on the right. */
.pa-talk { display: flex; flex-direction: column; gap: 4px; margin: 1.5em 0 1.7em; padding: 16px; border: 1px solid var(--line); border-radius: 16px; background: var(--panel); font-family: var(--font-display); }
.pa-line { display: flex; flex-direction: column; align-items: flex-start; max-width: 80%; }
.pa-line.is-c { align-self: flex-end; align-items: flex-end; }
.pa-line.is-first:not(:first-child) { margin-top: 10px; }
.pa-who { margin: 0 4px 4px; font: 500 10.5px/1.4 var(--font-mono); letter-spacing: .06em; text-transform: uppercase; color: var(--muted); }
.pa-line.is-c .pa-who { color: var(--accent); }
.pa-line p { margin: 0; padding: 9px 14px; font-size: .93em; line-height: 1.55; border-radius: 16px; }
.pa-line.is-i p { background: var(--code-bg); color: var(--ink); border-start-start-radius: 5px; }
.pa-line.is-c p { background: var(--accent-soft); color: var(--ink); border-start-end-radius: 5px; }
.pa-line.is-c p code { background: color-mix(in srgb, var(--panel) 60%, transparent); }
.pa-line.is-i:not(.is-first) p { border-start-start-radius: 5px; }
.pa-line.is-c:not(.is-first) p { border-start-end-radius: 5px; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }

/* Architecture stages and bad / good / great approaches */
.pa-board figcaption { display: flex; flex-wrap: wrap; align-items: baseline; gap: 4px 10px; margin-top: 10px; font-size: 14px; color: var(--soft-ink); }
.pa-board figcaption span { font: 500 11px/1.4 var(--font-mono); letter-spacing: .07em; text-transform: uppercase; color: var(--accent); }
.pa-newkey { font-style: normal; font: 500 11px/1.4 var(--font-mono); color: var(--good); }
.pa-newkey::before { content: ""; display: inline-block; width: 8px; height: 8px; margin-inline-end: 6px; border-radius: 3px; border: 1.5px solid var(--good); vertical-align: 0; }
.pa-board { margin: 1.4em 0 1.8em; }
.pa-board .wb-body { height: 360px; }
.pa-body figure { margin-inline: 0; }
.wb-node.is-new .wb-box { stroke: var(--good); stroke-width: 2; }
.wb-edge.is-new .wb-line { stroke: var(--good); }
.wb-new-bg { fill: var(--good); }
.wb-new { font: 600 9px var(--font-mono); letter-spacing: .06em; fill: var(--panel); pointer-events: none; }
.pa-tier { display: flex; flex-wrap: wrap; align-items: baseline; gap: 2px 12px; padding-top: 14px; border-top: 1px solid var(--line); }
.pa-tier .pa-kick { display: inline-block; margin: 0; padding: 3px 8px; border-radius: 5px; font-size: 10.5px; }
.pa-tier.t-bad .pa-kick { background: color-mix(in srgb, var(--tier-bad) 14%, transparent); color: var(--tier-bad); }
.pa-tier.t-good .pa-kick { background: var(--amber-soft); color: var(--amber); }
.pa-tier.t-great .pa-kick { background: color-mix(in srgb, var(--good) 15%, transparent); color: var(--good); }

.pa-note { margin: 1.6em 0; padding: 14px 18px 4px; border-inline-start: 2px solid var(--good); border-radius: 0 12px 12px 0; background: color-mix(in srgb, var(--good) 8%, transparent); font-family: var(--font-display); font-size: .93em; }
.pa-note-k { margin: 0 0 6px !important; font: 500 11px/1.3 var(--font-mono) !important; letter-spacing: .07em; text-transform: uppercase; color: var(--good) !important; }
.pa-note p { margin: 0 0 10px; color: var(--ink); }

.pa-widget, .pa-board { margin: 2em 0; font-family: var(--font-display); }
.pa-board .wb-body { height: 470px; }
.pa-code { position: relative; margin: 1.4em 0; }
.pa-code .pq-code { margin: 0; padding-top: 14px; font-size: 13px; line-height: 1.65; }
.pa-body pre code { font: inherit; padding: 0; background: none; border-radius: 0; color: inherit; overflow-wrap: normal; }
.pa-table { margin: 1.6em 0; overflow-x: auto; border: 1px solid var(--line); border-radius: 12px; background: var(--panel); font-family: var(--font-display); }
.pa-table table { width: 100%; border-collapse: collapse; font-size: 14px; line-height: 1.45; font-variant-numeric: tabular-nums; }
.pa-table th { text-align: start; font: 500 11px/1.3 var(--font-mono); letter-spacing: .05em; text-transform: uppercase; color: var(--muted); padding: 11px 12px; border-bottom: 1px solid var(--line); white-space: nowrap; }
.pa-table td { padding: 11px 12px; border-bottom: 1px solid var(--line); color: var(--soft-ink); vertical-align: top; }
.pa-table tr:last-child td { border-bottom: 0; }
.pa-table td:first-child { color: var(--ink); font-weight: 500; }

.pa-end { display: flex; flex-wrap: wrap; gap: 12px; align-items: stretch; margin-top: 3em; padding-top: 24px; border-top: 1px solid var(--line); font-family: var(--font-display); }
.pa-end .btn { border: 0; align-self: stretch; padding-inline: 18px; }
.pa-next { display: grid; gap: 2px; padding: 10px 16px; border: 1px solid var(--line); border-radius: 10px; text-decoration: none; color: var(--ink); font-size: 15px; font-weight: 500; }
.pa-next span { font: 500 10.5px/1.4 var(--font-mono); letter-spacing: .08em; text-transform: uppercase; color: var(--muted); }

.pa-progress { position: fixed; inset: 0 0 auto; z-index: 30; height: 2px; pointer-events: none; }
.pa-progress i { display: block; height: 100%; background: var(--accent); transform: scaleX(0); transform-origin: 0 50%; }

@media (hover: hover) {
  .pq-crumbs a:hover, .pw-views a:hover { color: var(--ink); }
  .pa-time button:hover { border-top-color: color-mix(in srgb, var(--accent) 55%, var(--line)); color: var(--ink); }
  .pa-pop button:hover { color: var(--ink); background: var(--paper); }
  .pa-next:hover { border-color: var(--accent); }
}
@media (prefers-reduced-motion: no-preference) {
  .pa-time button:active, .pa-copy:active { scale: .96; }
  .pa-next:active { scale: .985; }
  .pa-next, .pa-copy { transition: border-color .2s, color .2s, scale .15s var(--ease); }
}
.pw-readlink { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; margin-top: 18px; padding: 14px 16px; border-radius: 12px; background: var(--accent-soft); color: var(--ink); text-decoration: none; font-size: 14.5px; }
.pw-readlink b { font-weight: 500; color: var(--accent); }

@media (max-width: 720px) {
  .pw-views { gap: 20px; }
  .pa-time ol { flex-direction: column; gap: 0; }
  .pa-time li { flex: none !important; }
  .pa-time button { grid-template-columns: 1fr auto; padding: 9px 2px 9px 12px; border-top: 0; border-inline-start: 3px solid var(--line); }
  .pa-time button.on { border-inline-start-color: var(--accent); }
  .pa-line { max-width: 90%; }
  .pa-talk { padding: 12px; }
  .pa-sum { padding: 16px 16px 6px; }
  .pa-board .wb-body { height: 400px; }
}
.pa-body .pa-end .btn { color: var(--paper); text-decoration: none; }
.pa-body .pa-next { color: var(--ink); text-decoration: none; }

/* Article page: one centred column; contents in a popover on a sticky reading bar */
.pa-page { max-width: 800px; margin: 0 auto; }
body.pa-focus .pa-page { max-width: 860px; }
.pa-bar { position: sticky; top: 12px; z-index: 8; display: flex; justify-content: flex-end; height: 0; margin: -6px 0 6px; }
.pa-bar-in { position: relative; display: flex; gap: 6px; font-family: var(--font-display); }
.pa-btn { max-width: 260px; box-shadow: 0 4px 14px -10px rgba(0, 0, 0, .35); }
.pa-btn span { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.pa-btn[aria-pressed="true"], .pa-btn[aria-expanded="true"] { border-color: color-mix(in srgb, var(--accent) 50%, var(--line)); color: var(--accent); }
.pa-pop { position: absolute; top: calc(100% + 8px); inset-inline-end: 0; width: min(340px, calc(100vw - 32px)); max-height: min(70vh, 560px); overflow-y: auto; overscroll-behavior: contain; padding: 12px 8px 8px; border: 1px solid var(--line); border-radius: 14px; background: var(--panel); box-shadow: 0 18px 50px -20px rgba(0, 0, 0, .45); }
.pa-pop > p { margin: 0 8px 8px; font: 500 11px/1.3 var(--font-mono); letter-spacing: .08em; text-transform: uppercase; color: var(--muted); }
.pa-pop ol { list-style: none; margin: 0; padding: 0; display: grid; gap: 1px; }
.pa-pop button { display: block; width: 100%; text-align: start; padding: 7px 10px; border: 0; border-radius: 8px; background: none; color: var(--soft-ink); font: 400 13.5px/1.4 var(--font-display); cursor: pointer; }
.pa-pop button.on { background: var(--accent-soft); color: var(--accent); }
.pa-toc-k { display: block; font: 400 10.5px/1.5 var(--font-mono); letter-spacing: .04em; color: var(--muted); }
.pa-pop button.on .pa-toc-k { color: var(--accent); }
@media (prefers-reduced-motion: no-preference) {
  .pa-pop:not([hidden]) { animation: paPop .18s var(--ease); transform-origin: top right; }
  .pa-btn:active { scale: .96; }
}
@keyframes paPop { from { opacity: 0; transform: scale(.97) translateY(-4px); } }
@media (max-width: 900px) {
  .pa-bar { top: calc(64px + env(safe-area-inset-top, 0px)); }
  .pa-btn[data-focus] { display: none; }
}

/* ---------- Readable code, APIs and napkin maths ---------- */
.pa-codewrap { margin: 1.4em 0 1.6em; font-family: var(--font-display); }
.pa-codewrap .code { margin: 0; }
.pa-codewrap.has-notes .code { border-radius: 10px 10px 0 0; }
.pa-body .code pre { font-size: 13.5px; line-height: 1.7; }
.pa-body .code pre code { color: #d3dae3; }
.cn { display: inline-grid; place-items: center; min-width: 18px; height: 18px; padding: 0 4px; border-radius: 9px; background: #2c4fd6; color: #fff; font: 600 10.5px/1 var(--font-mono); vertical-align: 1px; }
.pa-notes { list-style: none; margin: 0 !important; padding: 12px 16px !important; border: 1px solid var(--line); border-top: 0; border-radius: 0 0 10px 10px; background: var(--panel); display: grid; gap: 8px; font-size: 14.5px; line-height: 1.55; color: var(--soft-ink); }
.pa-notes li { display: grid; grid-template-columns: 24px minmax(0, 1fr); gap: 8px; align-items: baseline; margin: 0 !important; }

.apis { display: grid; gap: 12px; margin: 1.4em 0 1.6em; font-family: var(--font-display); }
.api { border: 1px solid var(--line); border-radius: 12px; background: var(--panel); overflow: hidden; }
.api-head { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; padding: 12px 16px; border-bottom: 1px solid var(--line); background: color-mix(in srgb, var(--code-bg) 55%, var(--panel)); }
.api-m { flex: none; padding: 4px 8px; border-radius: 6px; font: 600 11.5px/1 var(--font-mono); letter-spacing: .04em; }
.m-get { background: color-mix(in srgb, var(--accent) 16%, transparent); color: var(--accent); }
.m-post { background: color-mix(in srgb, var(--good) 16%, transparent); color: var(--good); }
.m-put, .m-patch { background: var(--amber-soft); color: var(--amber); }
.m-delete { background: color-mix(in srgb, var(--tier-bad) 14%, transparent); color: var(--tier-bad); }
.m-call { background: var(--code-bg); color: var(--soft-ink); }
.api-path { font: 500 15px/1.4 var(--font-mono); color: var(--ink); background: none !important; padding: 0 !important; overflow-wrap: anywhere; }
.api-head > .api-path:not(code) { font-family: var(--font-display); font-size: 15px; }
.api-desc { margin: 0 !important; padding: 10px 16px 0; font-size: 14.5px !important; line-height: 1.5; color: var(--soft-ink); }
.api-row { display: grid; grid-template-columns: 96px minmax(0, 1fr); gap: 12px; align-items: baseline; padding: 10px 16px; }
.api-row + .api-row { border-top: 1px dashed var(--line); }
.api-desc + .api-row { padding-top: 12px; }
.api-k { font: 500 10.5px/1.6 var(--font-mono); letter-spacing: .07em; text-transform: uppercase; color: var(--muted); }
.api-json { display: block; padding: 8px 10px !important; border-radius: 8px; background: var(--code-bg); font: 400 13px/1.6 var(--font-mono) !important; white-space: pre-wrap; overflow-wrap: anywhere; color: var(--ink); }
.api-txt { font-size: 14.5px; line-height: 1.5; color: var(--soft-ink); }
.api-codes, .api-hdrs { list-style: none; margin: 0 !important; padding: 0 !important; display: grid; gap: 8px; }
.api-codes li { display: grid; grid-template-columns: 46px minmax(0, 1fr); gap: 10px; align-items: baseline; margin: 0 !important; }
.api-hdrs li { margin: 0 !important; }
.api-hdrs code { font-size: 13px !important; }
.api-hdrs b { font-weight: 600; color: var(--accent); }
.api-s { display: inline-block; padding: 3px 7px; border-radius: 6px; font: 600 11.5px/1 var(--font-mono); text-align: center; }
.s-2 { background: color-mix(in srgb, var(--good) 16%, transparent); color: var(--good); }
.s-3 { background: color-mix(in srgb, var(--accent) 16%, transparent); color: var(--accent); }
.s-4 { background: var(--amber-soft); color: var(--amber); }
.s-5 { background: color-mix(in srgb, var(--tier-bad) 14%, transparent); color: var(--tier-bad); }
.api .tk-a { color: var(--accent); } .api .tk-s { color: var(--good); } .api .tk-n, .api .tk-k { color: var(--amber); }

.calc { margin: 1.4em 0 1.6em; border: 1px solid var(--line); border-radius: 12px; background: var(--panel); overflow: hidden; font-family: var(--font-display); }
.calc-row { display: grid; grid-template-columns: minmax(110px, 0.8fr) minmax(0, 1.6fr) minmax(120px, 1fr); gap: 14px; align-items: baseline; padding: 10px 16px; }
.calc-row + .calc-row { border-top: 1px solid var(--line); }
.calc-h { padding-block: 9px; background: color-mix(in srgb, var(--code-bg) 55%, var(--panel)); }
.calc-h span { font: 500 10.5px/1.4 var(--font-mono); letter-spacing: .07em; text-transform: uppercase; color: var(--muted); }
.calc-l { font-size: 14.5px; font-weight: 500; color: var(--ink); }
.calc-w { font: 400 13.5px/1.5 var(--font-mono); color: var(--soft-ink); font-variant-numeric: tabular-nums; }
.calc-r { font: 600 14px/1.45 var(--font-mono); color: var(--accent); font-variant-numeric: tabular-nums; }
@media (max-width: 720px) {
  .calc-row { grid-template-columns: minmax(0, 1fr) auto; gap: 2px 12px; }
  .calc-w { grid-column: 1 / -1; grid-row: 2; }
  .calc-h { display: none; }
  .api-row { grid-template-columns: minmax(0, 1fr); gap: 6px; }
}
.api-hdrs li { line-height: 1.45; }
.api-hdrs { gap: 6px !important; }
.pa-walk { counter-reset: walk; list-style: none; padding: 0 !important; margin: 0 0 1.6em !important; display: grid; gap: 10px; }
.pa-walk li { counter-increment: walk; position: relative; margin: 0 !important; padding-inline-start: 38px; }
.pa-walk li::before { content: counter(walk); position: absolute; inset-inline-start: 0; top: 2px; display: grid; place-items: center; width: 24px; height: 24px; border-radius: 50%; background: var(--accent-soft); color: var(--accent); font: 600 12px/1 var(--font-mono); }
.pa-board[data-stage=""] .wb-body { height: 470px; }

/* ---------- Engineering blogs ---------- */
.bl-co { font: 500 11px/1 var(--font-mono); letter-spacing: .06em; text-transform: uppercase; padding: 4px 7px; border-radius: 5px; background: var(--code-bg); color: var(--ink); }
.bl-kind { font: 500 10.5px/1 var(--font-mono); letter-spacing: .06em; text-transform: uppercase; padding: 4px 7px; border-radius: 5px; background: color-mix(in srgb, var(--tier-bad) 13%, transparent); color: var(--tier-bad); }
.bl-src { color: var(--accent); text-decoration: none; }
.bl-src:hover { text-decoration: underline; }
.pa-head .pw-lessons { margin-top: 14px; }
.bl-note { margin: 2.4em 0 0; padding: 14px 18px; border: 1px dashed var(--line); border-radius: 12px; font-family: var(--font-display); font-size: 14px; line-height: 1.6; color: var(--muted); }
.bl-note p { margin: 0 !important; }
.bl-note b { font-weight: 500; color: var(--soft-ink); }

/* Incident timelines */
.tl { list-style: none; margin: 1.4em 0 1.8em !important; padding: 0 !important; position: relative; font-family: var(--font-display); }
.tl::before { content: ""; position: absolute; top: 8px; bottom: 8px; inset-inline-start: 132px; width: 2px; background: var(--line); }
.tl li { position: relative; display: grid; grid-template-columns: 116px minmax(0, 1fr); gap: 34px; margin: 0 !important; padding: 7px 0; }
.tl li::before { content: ""; position: absolute; inset-inline-start: 127px; top: 14px; width: 12px; height: 12px; border-radius: 50%; background: var(--panel); border: 2px solid var(--line); box-sizing: border-box; }
.tl-t { font: 500 12.5px/1.6 var(--font-mono); color: var(--muted); text-align: end; font-variant-numeric: tabular-nums; }
.tl-e { font-size: 15px; line-height: 1.55; color: var(--soft-ink); }
.tl li.is-key::before { background: var(--tier-bad); border-color: var(--tier-bad); }
.tl li.is-key .tl-e { color: var(--ink); font-weight: 500; }
.tl li.is-key .tl-t { color: var(--tier-bad); }
@media (max-width: 720px) {
  .tl::before { inset-inline-start: 5px; }
  .tl li { grid-template-columns: minmax(0, 1fr); gap: 2px; padding-inline-start: 26px; }
  .tl li::before { inset-inline-start: 0; }
  .tl-t { text-align: start; }
}
.pa-bar + .pa-body { padding-top: 46px; }
.bl-badge { margin-inline-start: 6px; font: 500 10px/1 var(--font-mono); letter-spacing: .06em; text-transform: uppercase; padding: 4px 6px; border-radius: 5px; }
.bl-badge.b-latest { background: color-mix(in srgb, var(--good) 15%, transparent); color: var(--good); }
.bl-badge.b-landmark { background: var(--amber-soft); color: var(--amber); }
.bl-card .pq-card-top { justify-content: flex-start; }
.bl-card .pq-mins { margin-inline-start: auto; }
.pa-head .eyebrow .bl-badge { margin-inline-start: 0; }
.pa-head .eyebrow { gap: 8px; }
.bl-card .pq-card-top { flex-wrap: wrap; row-gap: 6px; }
.bl-card .pq-mins { white-space: nowrap; }

/* ---------- Low-level design ---------- */
.lld-sec { display: flex; align-items: center; gap: 10px; margin: 34px 0 4px; font-size: 21px; font-weight: 600; letter-spacing: -0.02em; }
.lld-sec span { display: grid; place-items: center; width: 26px; height: 26px; border-radius: 50%; background: var(--accent-soft); color: var(--accent); font: 500 13px/1 var(--font-mono); }
.lld-sec-p { margin: 0 0 14px; color: var(--muted); font-size: 14.5px; }
.uml { margin: 1.6em 0; padding: 0; border: 1px solid var(--line); border-radius: 12px; background: var(--paper); font-family: var(--font-display); }
.uml-scroll { overflow-x: auto; padding: 8px; }
.uml svg { display: block; width: 100%; height: auto; }
.uml-box { fill: var(--panel); stroke: color-mix(in srgb, var(--ink) 55%, var(--line)); stroke-width: 1.3; }
.uml-head { fill: var(--accent-soft); }
.k-interface .uml-head { fill: color-mix(in srgb, var(--good) 14%, var(--panel)); }
.k-enum .uml-head { fill: var(--amber-soft); }
.k-abstract .uml-head { fill: color-mix(in srgb, var(--accent) 9%, var(--panel)); }
.uml-name { font: 600 14px var(--font-display); fill: var(--ink); }
.uml-name.it { font-style: italic; }
.uml-st { font: 400 11px var(--font-mono); fill: var(--muted); }
.uml-m { font: 400 12px var(--font-mono); fill: var(--soft-ink); }
.uml-sep { stroke: var(--line); stroke-width: 1; }
.uml-rel { fill: none; stroke: color-mix(in srgb, var(--soft-ink) 85%, var(--line)); stroke-width: 1.4; }
.uml-rel.dashed { stroke-dasharray: 6 4; }
.uml-hollow { fill: var(--paper); stroke: color-mix(in srgb, var(--soft-ink) 85%, var(--line)); stroke-width: 1.4; }
.uml-solid { fill: color-mix(in srgb, var(--soft-ink) 85%, var(--line)); stroke: none; }
.uml-open { fill: none; stroke: color-mix(in srgb, var(--soft-ink) 85%, var(--line)); stroke-width: 1.4; stroke-linejoin: round; }
.uml-lab-bg { fill: var(--paper); stroke: var(--line); }
.uml-lab { font: 400 11.5px var(--font-mono); fill: var(--soft-ink); }
.code pre, .pq-code, .api-json, .pa-body code { font-variant-ligatures: none; font-feature-settings: "liga" 0, "calt" 0; }
/* sequence diagrams */
.sq-box { fill: var(--accent-soft); stroke: color-mix(in srgb, var(--accent) 40%, var(--line)); }
.sq-p { font: 600 13px var(--font-display); fill: var(--ink); }
.sq-life { stroke: var(--line); stroke-width: 1.5; stroke-dasharray: 4 4; }
.sq-msg { fill: none; stroke: color-mix(in srgb, var(--soft-ink) 85%, var(--line)); stroke-width: 1.5; }
.sq-msg.reply { stroke-dasharray: 5 4; }
.sq-head { fill: color-mix(in srgb, var(--soft-ink) 85%, var(--line)); }
.sq-ohead { fill: none; stroke: color-mix(in srgb, var(--soft-ink) 85%, var(--line)); stroke-width: 1.4; }
.sq-t { font: 400 12px var(--font-mono); fill: var(--ink); paint-order: stroke; stroke: var(--paper); stroke-width: 4px; }
.sq-t.reply { fill: var(--soft-ink); }
.sq-n { fill: var(--accent); font-weight: 600; }
.sq-note { fill: var(--wb-note); stroke: var(--wb-note-line); }
.sq-nt { font: 400 12px var(--font-display); fill: var(--wb-note-ink); }
/* live class-diagram editor */
.pw-uml { display: grid; grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.1fr); gap: 14px; align-items: start; }
.pw-uml .uml { margin: 0; }
.pw-uml-prev { min-height: 200px; border: 1px dashed var(--line); border-radius: 12px; }
.pw-uml-prev .uml { border: 0; }
.pw-none-p { margin: 0; padding: 30px 16px; text-align: center; color: var(--muted); font-size: 14px; }
.pw-uhelp { margin: 0 0 12px; font-size: 14px; }
.pw-uhelp summary { cursor: pointer; color: var(--accent); font-weight: 500; }
@media (max-width: 900px) { .pw-uml { grid-template-columns: minmax(0, 1fr); } }

/* ---------- Email sign-up and the Pro waitlist ---------- */
.sc-vh { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
.sc-signup { margin: 40px 0 8px; padding: 22px 22px 18px; border: 1px solid var(--line); border-radius: 14px; background: var(--panel); }
.sc-signup-k { font: 500 11px/1.4 var(--font-mono); letter-spacing: 0.08em; text-transform: uppercase; color: var(--accent); margin: 0 0 6px; }
.sc-signup h2 { font: 600 19px/1.3 var(--font-display); margin: 0 0 6px; color: var(--ink); border: 0; padding: 0; }
.sc-signup-copy p:last-child { margin: 0 0 14px; color: var(--soft-ink); font-size: 15px; line-height: 1.55; }
.sc-signup-form { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }
.sc-signup-form input { font: 15px/1.4 inherit; font-family: inherit; color: var(--ink); background: var(--paper); border: 1px solid var(--line); border-radius: 9px; padding: 11px 12px; min-width: 0; }
.sc-signup-form input { flex: 1 1 240px; }
.sc-signup-form input:focus { outline: 2px solid var(--accent); outline-offset: 1px; border-color: transparent; }
.sc-signup .btn { border: 0; cursor: pointer; }
.sc-signup .btn:disabled { opacity: .6; cursor: progress; }
.sc-signup-form.is-done input, .sc-signup-form.is-done .btn { display: none; }
.sc-signup-msg { flex: 1 0 100%; margin: 2px 0 0; min-height: 1.4em; font-size: 14px; color: var(--muted); }
.sc-signup-msg.is-good { color: var(--good); }
.sc-signup-msg.is-bad { color: var(--amber, #c77c12); }
.sc-signup-slot .sc-signup { margin-top: 28px; }

@media (max-width: 600px) {
  .sc-signup { padding: 18px 16px; }
  .sc-signup-form .btn { flex: 1 0 100%; justify-content: center; }
}

.sc-signup[hidden] { display: none; }

.pa-loading { max-width: 720px; margin: 80px auto; color: var(--muted); font-size: 15px; text-align: center; }
.pa-loading a { color: var(--accent); }


" + EXPORT_CSS + "