:root {
  --paper: #f7f7f5;
  --surface: #ffffff;
  --surface-2: #efefec;
  --ink: #141413;
  --ink-2: #4a4a46;
  --ink-3: #85857f;
  --line: #e0e0db;
  --accent: #2f5bd3;
  --accent-ink: #ffffff;
  --hi: rgba(47, 91, 211, .14);
  --code-bg: #1b1b1a;
  --code-ink: #e9e9e4;
  --code-tag: #8fb4ff;
  --code-at: #f2c27b;
  --code-st: #9fd6a6;

  /* layer hues */
  --l-network: #6b5bd2;
  --l-hosting: #2f7fd3;
  --l-backend: #1b9a8a;
  --l-html: #d9572b;
  --l-css: #2a6fdb;
  --l-js: #c99a06;
  --l-assets: #b4529b;
  --l-seo: #2d9b4e;
  --l-quality: #c2413b;
  --l-workflow: #6f6f69;

  --radius: 14px;
  --sans: ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", Inter, Roboto, sans-serif;
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #121212; --surface: #1b1b1a; --surface-2: #242422;
    --ink: #f0f0ec; --ink-2: #bdbdb6; --ink-3: #8a8a83; --line: #2e2e2b;
    --accent: #7ea2ff; --accent-ink: #0d0d0d; --hi: rgba(126, 162, 255, .18);
    --code-bg: #0c0c0c;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --paper: #121212; --surface: #1b1b1a; --surface-2: #242422;
  --ink: #f0f0ec; --ink-2: #bdbdb6; --ink-3: #8a8a83; --line: #2e2e2b;
  --accent: #7ea2ff; --accent-ink: #0d0d0d; --hi: rgba(126, 162, 255, .18);
  --code-bg: #0c0c0c;
  color-scheme: dark;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 72px; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }
body {
  margin: 0; background: var(--paper); color: var(--ink);
  font: 16px/1.6 var(--sans); -webkit-font-smoothing: antialiased;
}
a { color: var(--accent); }
code { font-family: var(--mono); font-size: .9em; }
h1, h2, h3 { line-height: 1.15; letter-spacing: -.02em; margin: 0; }
.wrap { max-width: 1120px; margin: 0 auto; padding: 0 16px; }
@media (min-width: 720px) { .wrap { padding: 0 32px; } }
.sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }
.skip { position: absolute; left: -9999px; }
.skip:focus { left: 16px; top: 12px; z-index: 20; background: var(--surface); padding: 8px 12px; border-radius: 8px; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; border-radius: 6px; }

/* nav */
.top {
  position: sticky; top: 0; z-index: 10;
  background: color-mix(in srgb, var(--paper) 82%, transparent);
  backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
}
.nav { display: flex; align-items: center; justify-content: space-between; height: 56px; gap: 16px; }
.brand { color: var(--ink); text-decoration: none; font-weight: 700; letter-spacing: -.01em; white-space: nowrap; }
.brand span { color: var(--ink-3); font-weight: 500; margin-left: 6px; }
.nav-links { display: flex; gap: 20px; overflow-x: auto; scrollbar-width: none; }
.nav-links a { color: var(--ink-2); text-decoration: none; font-size: 14px; white-space: nowrap; }
.nav-links a:hover { color: var(--ink); }
@media (max-width: 640px) { .brand span { display: none; } .nav-links { gap: 14px; } }

/* hero */
.hero { padding: 72px 16px 24px; }
@media (min-width: 720px) { .hero { padding: 104px 32px 40px; } }
.eyebrow { text-transform: uppercase; letter-spacing: .12em; font-size: 12px; font-weight: 600; color: var(--ink-3); margin: 0 0 16px; }
.hero h1 { font-size: clamp(40px, 8vw, 84px); font-weight: 800; letter-spacing: -.04em; }
.lede { font-size: clamp(17px, 2.2vw, 21px); color: var(--ink-2); max-width: 62ch; margin: 24px 0 0; }
.thesis {
  margin: 28px 0 0; padding: 16px 20px; max-width: 62ch;
  border-left: 3px solid var(--accent); background: var(--surface); border-radius: 0 10px 10px 0;
}

/* blocks */
.block { padding-top: 72px; padding-bottom: 8px; }
.block-head { display: flex; gap: 16px; align-items: baseline; margin-bottom: 28px; }
.num { font: 600 13px var(--mono); color: var(--ink-3); }
.block-head h2 { font-size: clamp(28px, 4vw, 40px); font-weight: 750; }
.block-head p { color: var(--ink-2); margin: 8px 0 0; max-width: 64ch; }

.btn {
  font: 600 14px var(--sans); color: var(--ink); background: var(--surface);
  border: 1px solid var(--line); border-radius: 10px; padding: 8px 14px; cursor: pointer; min-height: 40px;
}
.btn:hover { border-color: var(--ink-3); }
.btn-primary { background: var(--ink); color: var(--paper); border-color: var(--ink); }
.chips { display: flex; flex-wrap: wrap; gap: 8px; }
.chip {
  font: 500 13px var(--sans); color: var(--ink-2); background: var(--surface);
  border: 1px solid var(--line); border-radius: 999px; padding: 5px 12px; cursor: pointer;
  display: inline-flex; align-items: center; gap: 6px;
}
.chip:hover { color: var(--ink); border-color: var(--ink-3); }
.chip[aria-pressed="true"] { background: var(--ink); color: var(--paper); border-color: var(--ink); }
.dot { width: 8px; height: 8px; border-radius: 50%; flex: none; }

/* journey */
.journey { display: grid; gap: 16px; }
.diagram-frame { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 8px; }
#journey-svg { display: block; width: 100%; height: auto; }
.journey-panel { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 20px; }
.controls { display: flex; align-items: center; gap: 8px; margin-bottom: 16px; }
.count { margin-left: auto; font: 500 13px var(--mono); color: var(--ink-3); }
#j-title { font-size: 22px; margin-bottom: 8px; }
#j-text { color: var(--ink-2); margin: 0 0 14px; min-height: 4.8em; max-width: 80ch; }
@media (max-width: 640px) { #j-text { min-height: 9.6em; } }
.steps { list-style: none; padding: 0; margin: 18px 0 0; display: flex; flex-wrap: wrap; gap: 6px; border-top: 1px solid var(--line); padding-top: 14px; }
.steps button {
  font: 500 12px var(--sans); color: var(--ink-3); background: none; border: 1px solid var(--line);
  border-radius: 999px; padding: 4px 10px; cursor: pointer;
}
.steps button[aria-current="step"] { color: var(--paper); background: var(--accent); border-color: var(--accent); }

/* svg diagram */
.node rect { fill: var(--surface-2); stroke: var(--line); stroke-width: 1.5; transition: fill .3s, stroke .3s; }
.node .n-label { fill: var(--ink); font: 600 14px var(--sans); }
.node .n-sub { fill: var(--ink-3); font: 500 11px var(--sans); }
.node.on rect { fill: color-mix(in srgb, var(--accent) 14%, var(--surface)); stroke: var(--accent); }
.wire { stroke: var(--line); stroke-width: 2; stroke-dasharray: 4 5; fill: none; transition: stroke .3s; }
.wire.on { stroke: var(--accent); stroke-dasharray: none; }
.packet { fill: var(--accent); }
.packet-ring { fill: none; stroke: var(--accent); opacity: .35; }

/* layer stack */
.stack { display: grid; gap: 6px; }
.layer {
  display: grid; grid-template-columns: 6px 1fr auto; gap: 16px; align-items: center;
  width: 100%; text-align: left; font: inherit; color: inherit;
  background: var(--surface); border: 1px solid var(--line); border-radius: 12px;
  padding: 14px 18px 14px 0; cursor: pointer; overflow: hidden;
  transition: transform .2s, border-color .2s;
}
.layer:hover { transform: translateX(4px); border-color: var(--ink-3); }
.layer .bar { align-self: stretch; margin: -14px 0; }
.layer b { font-size: 17px; }
.layer p { margin: 2px 0 0; color: var(--ink-2); font-size: 14px; }
.layer .who { font: 500 12px var(--mono); color: var(--ink-3); text-align: right; white-space: nowrap; }
.layer .who em { display: block; font-style: normal; color: var(--ink-2); }
.stack-label { font: 600 11px var(--mono); text-transform: uppercase; letter-spacing: .1em; color: var(--ink-3); margin: 10px 0 2px; }
@media (max-width: 560px) { .layer { grid-template-columns: 6px 1fr; } .layer .who { grid-column: 2; text-align: left; } }

/* head anatomy */
.anatomy { display: grid; gap: 20px; }
@media (min-width: 960px) { .anatomy { grid-template-columns: 1.1fr 1fr; align-items: start; } }
.code {
  margin: 0; background: var(--code-bg); color: var(--code-ink); border-radius: var(--radius);
  padding: 20px; font: 13px/1.7 var(--mono); overflow-x: auto; tab-size: 2;
}
.code .tag { color: var(--code-tag); }
.code .at { color: var(--code-at); }
.code .st { color: var(--code-st); }
.head-code .ln { display: inline-block; border-radius: 6px; padding: 0 4px; margin: 0 -4px; cursor: pointer; transition: background .2s; }
.head-code .ln.hot { background: rgba(126, 162, 255, .25); }
.surfaces { display: grid; gap: 14px; }
.surface { margin: 0; background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 14px 16px 16px; }
.surface figcaption { font: 600 11px var(--mono); text-transform: uppercase; letter-spacing: .1em; color: var(--ink-3); margin-bottom: 10px; }
[data-k] { transition: background .2s, box-shadow .2s; border-radius: 4px; }
.surfaces .hot { background: var(--hi); box-shadow: 0 0 0 3px var(--hi); }
.serp-site { display: flex; gap: 10px; align-items: center; font-size: 13px; }
.serp-site small { display: block; color: var(--ink-3); font-size: 12px; }
.fav { width: 26px; height: 26px; border-radius: 50%; display: grid; place-items: center; background: var(--ink); color: var(--paper); font-weight: 700; font-size: 13px; flex: none; }
.serp-title { color: var(--accent); font-size: 19px; margin: 6px 0 2px; }
.serp-desc { color: var(--ink-2); font-size: 14px; }
.card-prev { border: 1px solid var(--line); border-radius: 10px; overflow: hidden; }
.card-img {
  aspect-ratio: 1200 / 630; max-height: 150px; width: 100%; display: grid; place-items: center; align-content: center; gap: 2px;
  background: linear-gradient(135deg, #2f5bd3, #6b5bd2); color: #fff; border-radius: 0;
}
.card-img span { font: 500 11px var(--mono); opacity: .7; }
.card-img b { font-size: 22px; letter-spacing: -.02em; }
.card-body { padding: 10px 12px; font-weight: 600; font-size: 14px; }
.card-body small { display: block; color: var(--ink-3); font-weight: 400; font-size: 12px; }
.ai-q { margin: 0 0 8px; font-weight: 600; }
.ai-a { margin: 0; color: var(--ink-2); font-size: 15px; }
.cite { font: 500 11px var(--mono); background: var(--surface-2); padding: 2px 6px; border-radius: 999px; white-space: nowrap; }
.note { color: var(--ink-3); font-size: 14px; margin: 16px 0 0; max-width: 72ch; }

/* encyclopedia */
.enc-tools { display: grid; gap: 14px; margin-bottom: 20px; }
.search input {
  width: 100%; font: 16px var(--sans); color: var(--ink); background: var(--surface);
  border: 1px solid var(--line); border-radius: 12px; padding: 12px 16px;
}
.search input:focus { outline: 2px solid var(--accent); outline-offset: 0; border-color: transparent; }
.terms { display: grid; gap: 10px; }
@media (min-width: 720px) { .terms { grid-template-columns: 1fr 1fr; align-items: start; } }
.term {
  background: var(--surface); border: 1px solid var(--line); border-radius: 12px;
  border-left: 4px solid var(--c, var(--line));
}
.term.open { grid-column: 1 / -1; }
.term summary {
  list-style: none; cursor: pointer; padding: 14px 16px; display: grid; gap: 2px;
}
.term summary::-webkit-details-marker { display: none; }
.term .t-name { font-weight: 700; font-size: 16px; display: flex; justify-content: space-between; gap: 12px; }
.term .t-layer { font: 500 11px var(--mono); color: var(--ink-3); white-space: nowrap; }
.term .t-short { color: var(--ink-2); font-size: 14px; }
.term .t-body { padding: 0 16px 16px; }
.term .t-body p { margin: 0 0 12px; max-width: 74ch; }
.term .code { font-size: 12.5px; padding: 14px 16px; margin-bottom: 12px; white-space: pre; }
.term .rel { font-size: 13px; color: var(--ink-3); display: flex; flex-wrap: wrap; gap: 6px; align-items: center; }
.term.flash { animation: flash 1.2s ease-out; }
@keyframes flash { from { box-shadow: 0 0 0 4px var(--hi); } to { box-shadow: 0 0 0 4px transparent; } }
.empty { color: var(--ink-3); }

.foot { padding-top: 64px; padding-bottom: 48px; color: var(--ink-3); font-size: 14px; }
.foot p { border-top: 1px solid var(--line); padding-top: 20px; margin: 0; }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { transition: none !important; animation: none !important; }
}

/* ── basics page ───────────────────────────────────── */
.analogy { display: grid; gap: 10px; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); }
.ana {
  background: var(--surface); border: 1px solid var(--line); border-radius: 12px;
  border-top: 4px solid var(--c); padding: 16px;
}
.ana-k { font: 600 11px var(--mono); text-transform: uppercase; letter-spacing: .08em; color: var(--ink-3); }
.ana h3 { font-size: 18px; margin: 6px 0 6px; }
.ana h3 code { font-size: 13px; font-weight: 500; color: var(--ink-3); margin-left: 4px; }
.ana p { margin: 0; color: var(--ink-2); font-size: 15px; }

.flow { list-style: none; padding: 0; margin: 0; display: grid; gap: 10px; counter-reset: f; }
@media (min-width: 900px) { .flow { grid-template-columns: repeat(5, 1fr); } }
.flow li {
  counter-increment: f; position: relative; background: var(--surface); border: 1px solid var(--line);
  border-radius: 12px; padding: 16px; display: grid; gap: 4px;
}
.flow li::before { content: counter(f); font: 600 12px var(--mono); color: var(--accent); }
.flow b { font-size: 16px; }
.flow span { color: var(--ink-2); font-size: 14px; }
@media (min-width: 900px) {
  .flow li:not(:last-child)::after {
    content: "→"; position: absolute; right: -10px; top: 50%; transform: translate(50%, -50%);
    color: var(--ink-3); background: var(--paper); line-height: 1; padding: 2px 0; z-index: 1;
  }
}
@media (max-width: 899px) {
  .flow li:not(:last-child)::after {
    content: "↓"; position: absolute; left: 50%; bottom: -10px; transform: translate(-50%, 50%);
    color: var(--ink-3); background: var(--paper); padding: 0 6px; z-index: 1;
  }
}

.found { display: grid; gap: 10px; }
@media (min-width: 720px) { .found { grid-template-columns: 1fr 1fr; } }
.found-step { display: flex; gap: 14px; background: var(--surface); border: 1px solid var(--line); border-radius: 12px; padding: 16px; }
.found-step span {
  flex: none; width: 30px; height: 30px; border-radius: 50%; display: grid; place-items: center;
  background: var(--l-seo); color: #fff; font-weight: 700; font-size: 14px;
}
.found-step p { margin: 0; color: var(--ink-2); }
.found-step b { color: var(--ink); }
#found .thesis { margin-top: 20px; }

.timeline { list-style: none; padding: 0; margin: 0; position: relative; }
.timeline::before { content: ""; position: absolute; left: 63px; top: 0; bottom: 0; width: 2px; background: var(--line); }
.timeline .era { position: relative; margin: 28px 0 12px; padding-left: 88px; }
.timeline .era:first-child { margin-top: 0; }
.timeline .era::before {
  content: ""; position: absolute; left: 56px; top: 6px; width: 16px; height: 16px; border-radius: 4px; background: var(--c);
}
.timeline .era h3 { font-size: 20px; }
.timeline .era p { margin: 2px 0 0; color: var(--ink-3); font-size: 14px; }
.ev { display: grid; grid-template-columns: 48px 1fr; gap: 40px; padding: 10px 0; position: relative; }
.ev::before {
  content: ""; position: absolute; left: 59px; top: 18px; width: 10px; height: 10px; border-radius: 50%;
  background: var(--paper); border: 2px solid var(--ink-3);
}
.ev.now::before { background: var(--accent); border-color: var(--accent); }
.ev time { font: 600 14px var(--mono); color: var(--ink-2); text-align: right; padding-top: 2px; }
.ev b { font-size: 16px; }
.ev p { margin: 4px 0 6px; color: var(--ink-2); max-width: 68ch; }
.tag {
  display: inline-block; font: 500 12px var(--mono); color: var(--ink-2); text-decoration: none;
  background: var(--surface); border: 1px solid var(--line); border-radius: 999px; padding: 2px 10px; margin: 2px 4px 0 0;
}
.tag::before { content: "↗ "; color: var(--ink-3); }
.tag:hover { color: var(--ink); border-color: var(--ink-3); }
@media (max-width: 560px) {
  .timeline::before { left: 7px; }
  .timeline .era { padding-left: 32px; }
  .timeline .era::before { left: 0; }
  .ev { grid-template-columns: 1fr; gap: 2px; padding-left: 32px; }
  .ev::before { left: 3px; top: 15px; }
  .ev time { text-align: left; }
}
.ev .src { margin: 6px 0 0; font-size: 12.5px; color: var(--ink-3); line-height: 1.5; }
.ev .src a { color: var(--ink-3); text-underline-offset: 2px; }
.ev .src a:hover { color: var(--accent); }

/* ── term pages (generated by scripts/build.mjs) ───── */
.term .t-link { font-size: 13px; margin: 12px 0 0; }
.tp { max-width: 760px; padding-top: 48px; }
.tp h1 { font-size: clamp(36px, 6vw, 56px); font-weight: 800; letter-spacing: -.03em; margin: 0; }
.tp h2 { font-size: 20px; font-weight: 700; margin: 40px 0 12px; }
.tp .lede { margin-top: 12px; }
.tp-crumb { font: 500 13px var(--mono); color: var(--ink-3); margin: 0 0 16px; }
.tp-crumb a { color: var(--ink-3); }
.tp-body { border-left: 4px solid var(--c); padding-left: 20px; margin-top: 32px; }
.tp-body p { font-size: 17px; max-width: 68ch; margin: 0 0 16px; }
.tp-body .code { font-size: 13px; padding: 14px 16px; white-space: pre; overflow-x: auto; }
.tp .chips a.chip { text-decoration: none; display: inline-flex; align-items: center; gap: 6px; }
.tp-steps { padding-left: 20px; color: var(--ink-2); }
.tp-steps li { margin-bottom: 10px; }
.tp-layer { color: var(--ink-2); margin: 0 0 12px; }
.tp-back { margin-top: 40px; }
.tp-group { border-top: 4px solid var(--c); padding-top: 4px; margin-top: 40px; }
.tp-group dl { display: grid; grid-template-columns: minmax(140px, max-content) 1fr; gap: 8px 20px; margin: 0; }
.tp-group dt { font-weight: 600; }
.tp-group dd { margin: 0; color: var(--ink-2); }
@media (max-width: 560px) { .tp-group dl { grid-template-columns: 1fr; gap: 2px; } .tp-group dd { margin-bottom: 10px; } }