:root {
  --paper: #fbfaf6;
  --surface: #ffffff;
  --surface-soft: #f3f0e9;
  --ink: #242426;
  --muted: #62666b;
  --line: #d9d5cc;
  --accent: #8f1738;
  --accent-dark: #68102a;
  --blue: #176b87;
  --teal: #25756f;
  --gold: #a46212;
  --danger: #a13232;
  --success: #2f6f4e;
  --focus: #0879b5;
  --utility-height: 3.7rem;
  --side-nav: 15.5rem;
  --measure: 72ch;
  --radius: 0.7rem;
  --shadow: 0 0.5rem 1.6rem rgb(35 35 38 / 7%);
  --font: Inter, "Noto Sans", "Noto Sans JP", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --mono: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
}

* { box-sizing: border-box; }
html { color-scheme: light; scroll-behavior: smooth; }
body { margin: 0; color: var(--ink); background: var(--paper); font: 1rem/1.65 var(--font); }
button, input, select { font: inherit; }
a { color: var(--blue); text-underline-offset: 0.18em; }
a:hover { color: var(--accent); }
a:focus-visible, button:focus-visible, input:focus-visible, select:focus-visible, summary:focus-visible {
  outline: 0.2rem solid var(--focus); outline-offset: 0.18rem;
}
h1, h2, h3 { line-height: 1.17; text-wrap: balance; }
h1 { margin: 0; font-size: clamp(2.15rem, 5.5vw, 4.35rem); letter-spacing: -0.035em; }
h2 { margin: 0; font-size: clamp(1.55rem, 3.4vw, 2.45rem); letter-spacing: -0.02em; }
h3 { margin: 0; font-size: clamp(1.08rem, 2vw, 1.28rem); }
p, li { max-width: var(--measure); }
code, pre { font-family: var(--mono); }
code { font-size: 0.92em; }
pre { margin: 0; padding: 1rem; overflow-x: auto; color: #eceff2; background: #20242a; border-radius: 0 0 var(--radius) var(--radius); font-size: 0.86rem; line-height: 1.55; }
table { width: 100%; border-collapse: collapse; }
th, td { padding: 0.7rem; border-bottom: 1px solid var(--line); text-align: left; vertical-align: top; }
th { background: var(--surface-soft); }
.skip-link { position: fixed; left: -9999px; top: 0.6rem; z-index: 200; padding: 0.6rem 0.8rem; color: var(--ink); background: var(--surface); }
.skip-link:focus { left: 0.6rem; }
.course-layout { min-height: 100vh; }
.course-rail {
  position: sticky; top: 0; z-index: 30; display: flex; align-items: center; justify-content: space-between; gap: 1rem; width: 100%; min-height: var(--utility-height); padding: 0.5rem max(0.8rem, calc((100% - 86rem) / 2));
  color: #f9f7f4; background: #29292c; border-bottom: 0.22rem solid var(--accent);
}
.rail-home { flex: 0 0 auto; color: #fff; text-decoration: none; font-size: 0.9rem; font-weight: 720; white-space: nowrap; }
.rail-home:hover { color: #fff; text-decoration: underline; }
.rail-actions { flex: 0 0 auto; display: flex; align-items: center; gap: 0.4rem; }
.rail-actions a { display: block; padding: 0.55rem 0.7rem; color: #fff; border: 1px solid rgb(255 255 255 / 25%); border-radius: 0.35rem; text-align: center; text-decoration: none; font-size: 0.86rem; white-space: nowrap; }
.rail-actions .rail-jump { padding-inline: 0.55rem; background: transparent; }
.rail-actions .rail-download { background: var(--accent); border-color: var(--accent); }
.rail-actions a:hover { color: #fff; background: var(--accent-dark); border-color: var(--accent-dark); }
.chapter-nav {
  position: fixed; top: var(--utility-height); bottom: 0; left: 0; z-index: 20; width: var(--side-nav); padding: 1.25rem 1rem 1.5rem; overflow-y: auto; background: #f1efe9; border-right: 1px solid var(--line);
}
.chapter-nav-label { margin: 0 0 0.7rem; color: var(--muted); font-size: 0.72rem; font-weight: 800; letter-spacing: 0.1em; text-transform: uppercase; }
.chapter-nav-toggle { display: none; }
.chapter-nav nav { display: grid; gap: 0.14rem; }
.chapter-nav nav a { padding: 0.48rem 0.62rem; color: #424348; border-left: 0.2rem solid transparent; border-radius: 0.25rem; text-decoration: none; font-size: 0.87rem; }
.chapter-nav nav a:hover { color: var(--accent-dark); background: #fff; }
.chapter-nav nav a[aria-current="true"] { color: var(--accent-dark); background: #fff; border-left-color: var(--accent); font-weight: 730; }
.course-main { margin-left: var(--side-nav); }
.chapter-shell { width: min(100% - 3rem, 72rem); margin-inline: auto; padding-bottom: 5rem; }
.chapter-hero { display: grid; gap: 1.25rem; padding-top: 4.5rem; }
.hero-question { max-width: 62ch; margin: 0; padding-left: 1rem; border-left: 0.28rem solid var(--accent); font-size: clamp(1.15rem, 2vw, 1.45rem); font-weight: 680; }
.lead { max-width: 66ch; margin: 0; color: var(--muted); font-size: clamp(1.05rem, 1.8vw, 1.23rem); }
.hero-map article h2 { font-size: 1.18rem; }
.hero-map article p, .hero-map article li { font-size: 0.94rem; }
.table-wrap { overflow-x: auto; }
table caption { padding: 0.75rem; color: var(--muted); text-align: left; font-weight: 720; }
.optional { padding: 1rem; background: var(--surface); border: 1px solid var(--line); border-left: 0.3rem solid var(--blue); border-radius: var(--radius); }
.shape-stage { display: flex; flex-wrap: wrap; gap: 0.6rem; align-items: stretch; min-height: 8rem; margin-block: 1rem; padding: 1rem; background: #f5f2eb; border-radius: var(--radius); }
.axis-block { display: grid; min-width: 8rem; padding: 0.8rem; background: var(--surface); border: 1px solid var(--line); border-top: 0.3rem solid var(--blue); border-radius: 0.45rem; }
.axis-block span { color: var(--muted); font-size: 0.72rem; text-transform: uppercase; }
.axis-block strong { margin-block: 0.25rem; }
.axis-block b { color: var(--accent); font-size: 1.65rem; }
.matrix-grid { display: grid; grid-template-columns: repeat(4, minmax(2.5rem, 1fr)); gap: 0.35rem; max-width: 24rem; margin: 1rem auto; }
.matrix-grid span { display: grid; place-items: center; aspect-ratio: 1; background: #eeece6; border: 1px solid var(--line); border-radius: 0.3rem; font-family: var(--mono); }
.matrix-grid span.selected { color: #fff; background: var(--accent); border-color: var(--accent); }
.reshape-controls { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 1rem; }
.reshape-controls fieldset { display: flex; flex-wrap: wrap; gap: 0.6rem; min-width: 0; border: 1px solid var(--line); border-radius: var(--radius); }
.reshape-controls label { display: grid; gap: 0.25rem; min-width: 6rem; color: var(--muted); font-size: 0.85rem; }
.reshape-controls input { width: 100%; padding: 0.45rem; border: 1px solid var(--line); border-radius: 0.3rem; }
.reshape-result { display: flex; flex-wrap: wrap; align-items: center; gap: 0.8rem; margin-top: 1rem; padding: 1rem; border-left: 0.35rem solid var(--muted); background: var(--surface-soft); }
.reshape-result strong { font-family: var(--mono); font-size: 1.15rem; }
.reshape-result b { margin-left: auto; }
.reshape-result.valid { border-color: var(--success); }
.reshape-result.valid b { color: var(--success); }
.reshape-result.invalid { border-color: var(--danger); }
.reshape-result.invalid b { color: var(--danger); }
.broadcast-lines { display: grid; gap: 0.5rem; margin-block: 1rem; }
.broadcast-lines > div { display: grid; grid-template-columns: minmax(8rem, 1fr) minmax(6rem, 1fr) auto; align-items: center; gap: 0.7rem; padding: 0.7rem; background: var(--surface-soft); border-left: 0.3rem solid var(--success); }
.broadcast-lines > .incompatible { border-left-color: var(--danger); }
.broadcast-lines span { color: var(--muted); font-size: 0.82rem; }
.broadcast-lines b { font-size: 1.2rem; }
.matrix-operation { display: flex; align-items: center; justify-content: center; gap: 0.8rem; min-height: 13rem; overflow-x: auto; padding: 1rem; }
.matrix-operation i { color: var(--muted); font-size: 1.5rem; font-style: normal; }
.matrix-object { flex: 0 0 auto; text-align: center; }
.matrix-object > span { display: block; margin-bottom: 0.4rem; font-weight: 720; }
.matrix-object > div { display: grid; grid-template-columns: repeat(var(--cols), 2.5rem); gap: 0.2rem; padding: 0.5rem; border-inline: 0.16rem solid var(--ink); }
.matrix-object b { display: grid; place-items: center; height: 2.5rem; background: #f0ede6; font-family: var(--mono); font-weight: 500; }
.workflow-list { display: grid; gap: 0.65rem; padding: 0; list-style: none; counter-reset: steps; }
.workflow-list li { display: grid; grid-template-columns: 2.4rem minmax(0, 1fr); gap: 0.7rem; align-items: start; padding: 0.85rem; background: var(--surface); border: 1px solid var(--line); border-radius: 0.45rem; }
.workflow-list strong { display: grid; place-items: center; width: 2rem; height: 2rem; color: #fff; background: var(--accent); border-radius: 50%; }
.contract-example { margin-top: 1rem; padding: 1rem; background: #eef4f6; border-left: 0.35rem solid var(--blue); border-radius: var(--radius); }
.contract-example pre { border-radius: 0.45rem; }
.output-text { min-height: 0; padding: 0; color: inherit; background: transparent; border-radius: 0; white-space: pre-wrap; }
.summary-list { columns: 2; column-gap: 2rem; }
.summary-list li { break-inside: avoid; margin-bottom: 0.55rem; }
.review-card summary { display: grid; grid-template-columns: 2rem minmax(0, 1fr) auto; gap: 0.75rem; align-items: start; }
.review-card summary span { display: grid; place-items: center; width: 1.75rem; height: 1.75rem; color: #fff; background: var(--accent); border-radius: 50%; font-size: 0.78rem; }
.review-card summary em { color: var(--blue); font-size: 0.8rem; font-style: normal; font-weight: 650; white-space: nowrap; }
.review-card .answer { margin: 0.85rem 0 0 2.75rem; padding: 0.8rem 1rem; background: #e8f4f1; border-left: 0.28rem solid var(--teal); }
.review-card .answer p { margin: 0; }
.glossary-list { display: grid; grid-template-columns: minmax(9rem, 0.28fr) minmax(0, 1fr); gap: 0; }
.glossary-list dt, .glossary-list dd { margin: 0; padding: 0.75rem; border-bottom: 1px solid var(--line); }
.glossary-list dt { color: var(--accent-dark); font-weight: 760; }
.reference-list li { margin-block: 0.5rem; }
.hero { min-height: 72vh; display: grid; align-content: center; gap: 1.25rem; padding-block: 5rem 4rem; border-bottom: 1px solid var(--line); }
.eyebrow { margin: 0; color: var(--accent); font-size: 0.78rem; font-weight: 800; letter-spacing: 0.1em; text-transform: uppercase; }
.week-label { display: inline-block; margin-right: 0.3rem; padding: 0.12rem 0.42rem; color: #fff; background: var(--accent); border-radius: 999px; letter-spacing: 0.06em; }
.lead { max-width: 62ch; margin: 0; color: var(--muted); font-size: clamp(1.05rem, 1.8vw, 1.28rem); }
.question { max-width: 64ch; margin: 0.35rem 0 0; padding: 1rem 1.15rem; border-left: 0.3rem solid var(--accent); background: var(--surface); box-shadow: var(--shadow); }
.hero-map, .grid-2, .grid-3, .metrics { display: grid; gap: 1rem; }
.grid-2 > *, .grid-3 > * { min-width: 0; }
.hero-map { grid-template-columns: repeat(3, minmax(0, 1fr)); margin-top: 0.5rem; }
.hero-map article, .card, .definition, .evidence-case, .practice-card { min-width: 0; padding: 1.1rem; background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow); }
.hero-map strong, .hero-map span { display: block; }
.hero-map span { margin-top: 0.3rem; color: var(--muted); font-size: 0.92rem; }
.hero, .chapter-section, .chapter-footer { scroll-margin-top: calc(var(--utility-height) + 1rem); }
.chapter-section { padding-block: 4.5rem; border-bottom: 1px solid var(--line); }
.section-head { margin-bottom: 1.6rem; }
.section-head p:last-child { color: var(--muted); font-size: 1.05rem; }
.grid-2 { grid-template-columns: minmax(0, 1.05fr) minmax(20rem, 0.95fr); align-items: start; }
.grid-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.formula { max-width: 100%; margin-block: 1rem; padding: 0.85rem 1rem; overflow-x: auto; background: #f1ede4; border-left: 0.26rem solid var(--gold); border-radius: 0.35rem; font-family: var(--mono); }
.definition { margin-block: 1rem; box-shadow: none; border-left: 0.3rem solid var(--teal); }
.definition.warning { border-left-color: var(--gold); }
.definition.danger { border-left-color: var(--danger); }
.definition p:last-child { margin-bottom: 0; }
.lane { margin-block: 1rem; border-left: 0.35rem solid var(--accent); }
.lane.stretch { border-left-color: var(--blue); }
details { margin-block: 1rem; }
summary { cursor: pointer; font-weight: 720; }
details.card[open] summary { margin-bottom: 0.8rem; }
.explorer { min-width: 0; padding: 1.15rem; background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow); }
.explorer h3 { margin-bottom: 0.7rem; }
.control-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 0.8rem; margin-block: 1rem; }
.control-grid label { display: grid; gap: 0.35rem; color: var(--muted); font-size: 0.88rem; }
input[type="range"] { width: 100%; accent-color: var(--accent); }
select { width: 100%; padding: 0.5rem; color: var(--ink); background: var(--surface); border: 1px solid var(--line); border-radius: 0.35rem; }
.metrics { grid-template-columns: repeat(3, minmax(0, 1fr)); margin-block: 1rem; }
.metric { min-width: 0; padding: 0.75rem; background: var(--surface-soft); border-radius: 0.45rem; }
.metric small, .metric strong { display: block; }
.metric small { color: var(--muted); }
.metric strong { margin-top: 0.18rem; font-size: 1.2rem; overflow-wrap: anywhere; }
.graph { display: grid; grid-template-columns: repeat(7, minmax(3.4rem, 1fr)); gap: 0.35rem; align-items: center; margin-block: 1rem; overflow-x: auto; padding-bottom: 0.5rem; }
.graph-node { position: relative; min-width: 3.4rem; padding: 0.65rem 0.35rem; background: var(--surface-soft); border: 1px solid var(--line); border-radius: 0.4rem; text-align: center; font-family: var(--mono); font-size: 0.78rem; }
.graph-node:not(:last-child)::after { content: "→"; position: absolute; right: -0.6rem; top: 50%; z-index: 2; color: var(--muted); transform: translateY(-50%); }
.graph-node.active { color: #fff; background: var(--accent); border-color: var(--accent); }
.insight { min-height: 5rem; padding: 0.9rem 1rem; color: #183d3a; background: #e8f4f1; border-left: 0.3rem solid var(--teal); border-radius: 0.35rem; }
.mini-bars { display: grid; gap: 0.55rem; margin-block: 1rem; }
.bar-row { display: grid; grid-template-columns: 7rem minmax(0, 1fr) 4rem; gap: 0.55rem; align-items: center; font-size: 0.88rem; }
.bar-track { height: 0.72rem; overflow: hidden; background: #e3dfd6; border-radius: 999px; }
.bar-fill { height: 100%; width: 0; background: var(--blue); border-radius: inherit; transition: width 160ms ease; }
.bar-fill.bad { background: var(--danger); }
.code-card, .code-cell { min-width: 0; margin-block: 1.25rem; overflow: hidden; border: 1px solid #30343a; border-radius: var(--radius); box-shadow: var(--shadow); }
.code-head { display: flex; align-items: center; justify-content: space-between; gap: 1rem; padding: 0.65rem 0.9rem; color: #fff; background: #30343a; }
.code-head h3 { font-size: 0.95rem; }
.copy-button, .action-button { padding: 0.45rem 0.7rem; color: #fff; background: var(--accent); border: 0; border-radius: 0.35rem; cursor: pointer; }
.run-button { padding: 0.45rem 0.8rem; color: #fff; background: var(--accent); border: 0; border-radius: 0.35rem; cursor: pointer; }
.run-button:disabled { opacity: 0.65; cursor: wait; }
.output-panel { min-height: 5rem; padding: 0.9rem 1rem; color: #183d3a; background: #e8f4f1; border-top: 1px solid #c8ddd8; white-space: pre-wrap; overflow-wrap: anywhere; }
.output-panel strong { display: block; margin-bottom: 0.35rem; }
.output-panel p { margin: 0; }
.output-panel.is-error { color: #6d1e1e; background: #fae9e9; }
.copy-button:hover, .action-button:hover { background: var(--accent-dark); }
.evidence-case { margin-block: 1rem; border-left: 0.32rem solid var(--gold); }
.decision-list { display: grid; gap: 0.7rem; padding: 0; list-style: none; }
.decision-list li { padding: 0.8rem; background: var(--surface); border: 1px solid var(--line); border-radius: 0.4rem; }
.practice-grid { display: grid; gap: 0.8rem; }
.practice-card { box-shadow: none; }
.practice-card p { margin-top: 0; }
.table-wrap { overflow-x: auto; border: 1px solid var(--line); border-radius: var(--radius); }
.source-list li { margin-block: 0.4rem; }
.glossary-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 0.75rem; }
.glossary-grid div { padding: 0.9rem 1rem; background: var(--surface); border-left: 0.25rem solid var(--blue); }
.glossary-grid dt { font-weight: 780; }
.glossary-grid dd { margin: 0.25rem 0 0; color: var(--muted); }
.chapter-actions { display: flex; flex-wrap: wrap; gap: 0.7rem; margin-top: 2rem; }
.chapter-actions a { padding: 0.6rem 0.8rem; border: 1px solid var(--line); border-radius: 0.35rem; text-decoration: none; font-weight: 720; }
.chapter-footer { padding-block: 2.5rem; color: var(--muted); font-size: 0.9rem; }
.badge { display: inline-block; padding: 0.18rem 0.5rem; color: var(--accent-dark); background: #f7e8ed; border-radius: 999px; font-size: 0.75rem; font-weight: 750; }
.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; }

@media (max-width: 900px) {
  .course-rail { min-height: 3.45rem; padding: 0.45rem 0.7rem; }
  .chapter-nav { position: static; display: grid; grid-template-columns: minmax(0, 1fr) auto; align-items: center; gap: 0.55rem; width: min(100% - 1.25rem, 72rem); margin: 0.8rem auto 0; padding: 0.6rem; overflow: visible; background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow); }
  .chapter-nav-label { display: none; }
  .chapter-nav-toggle { display: block; justify-self: start; padding: 0.5rem 0.68rem; color: var(--ink); background: var(--surface-soft); border: 1px solid var(--line); border-radius: 0.35rem; font-weight: 730; cursor: pointer; }
  .chapter-nav-toggle::after { content: " +"; color: var(--accent); }
  .chapter-nav.is-open .chapter-nav-toggle::after { content: " −"; }
  .chapter-nav nav { display: none; grid-column: 1 / -1; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 0.25rem; padding-top: 0.5rem; border-top: 1px solid var(--line); }
  .chapter-nav.is-open nav { display: grid; }
  .chapter-nav nav a { border-left: 0; border-bottom: 0.15rem solid transparent; }
  .chapter-nav nav a[aria-current="true"] { border-left: 0; border-bottom-color: var(--accent); }
  .course-main { margin-left: 0; }
  .hero { min-height: auto; padding-top: 3.2rem; }
  .chapter-hero { padding-top: 2.5rem; }
}

@media (max-width: 720px) {
  .chapter-shell { width: min(100% - 1.25rem, 78rem); }
  .hero-map, .grid-2, .grid-3 { grid-template-columns: 1fr; }
  .control-grid, .metrics { grid-template-columns: 1fr 1fr; }
  .glossary-grid { grid-template-columns: 1fr; }
  .chapter-section { padding-block: 3.5rem; }
  .reshape-controls { grid-template-columns: 1fr; }
  .summary-list { columns: 1; }
}

@media (max-width: 440px) {
  .control-grid, .metrics { grid-template-columns: 1fr; }
  .course-rail { flex-wrap: wrap; gap: 0.3rem; padding: 0.4rem 0.45rem; }
  .rail-home { flex: 1 0 100%; font-size: 0.76rem; }
  .rail-actions { width: 100%; min-width: 0; justify-content: flex-end; gap: 0.22rem; overflow-x: auto; }
  .rail-actions a { padding: 0.42rem 0.38rem; font-size: 0.7rem; }
  .rail-actions .rail-jump { padding-inline: 0.28rem; }
  .bar-row { grid-template-columns: 5.5rem minmax(0, 1fr) 3.4rem; }
  .review-card summary { grid-template-columns: 1.8rem minmax(0, 1fr); }
  .review-card summary em { grid-column: 2; justify-self: start; }
  .review-card .answer { margin-left: 0; }
  .glossary-list { grid-template-columns: 1fr; }
  .glossary-list dt { border-bottom: 0; }
  .matrix-operation { justify-content: flex-start; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: 0.01ms !important; animation-iteration-count: 1 !important; transition-duration: 0.01ms !important; }
}

@media print {
  .course-rail, .chapter-nav, .copy-button, .interactive-only { display: none !important; }
  .course-main { margin: 0; }
  .chapter-shell { width: 100%; }
  .hero { min-height: 0; }
  .explorer, .card, .hero-map article { box-shadow: none; break-inside: avoid; }
}