:root {
  color-scheme: light;
  --paper: #f2f1ed;
  --paper-2: #e8e6e0;
  --ink: #20201e;
  --muted: #65635e;
  --line: #cbc8c0;
  --accent: #b33a2e;
  --accent-dark: #81271f;
  --surface: rgba(250, 249, 246, 0.88);
  --shadow: 0 22px 70px rgba(58, 49, 40, 0.12);
  --heading-copy-gap: 1.5rem;
  --sans: "Avenir Next", Avenir, "Helvetica Neue", Helvetica, Arial, sans-serif;
  --serif: "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, serif;
  --mono: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  --max: 1240px;
  --reading: 760px;
  --radius: 0px;
}

[data-theme="dark"] {
  color-scheme: dark;
  --paper: #1d1d1b;
  --paper-2: #282825;
  --ink: #eeece5;
  --muted: #aaa79f;
  --line: #45443f;
  --accent: #e06858;
  --accent-dark: #f18b7d;
  --surface: rgba(31, 31, 29, 0.9);
  --shadow: 0 22px 70px rgba(0, 0, 0, 0.3);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.65;
  text-rendering: optimizeLegibility;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: 20;
  pointer-events: none;
  opacity: 0.025;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 180 180' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.9' numOctaves='2' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)' opacity='.7'/%3E%3C/svg%3E");
}

a { color: inherit; text-decoration-color: color-mix(in srgb, var(--accent) 65%, transparent); text-underline-offset: 0.2em; }
a:hover { color: var(--accent-dark); }
img { display: block; max-width: 100%; }
button, input { font: inherit; }
button { color: inherit; }

.skip-link {
  position: fixed;
  left: 1rem;
  top: -5rem;
  z-index: 100;
  background: var(--ink);
  color: var(--paper);
  padding: 0.7rem 1rem;
}
.skip-link:focus { top: 1rem; }

.reading-progress {
  position: fixed;
  inset: 0 auto auto 0;
  z-index: 60;
  width: 0;
  height: 3px;
  background: var(--accent);
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  border-bottom: 1px solid var(--line);
  background: color-mix(in srgb, var(--paper) 88%, transparent);
  backdrop-filter: blur(14px);
}

.nav-shell {
  min-height: 68px;
  max-width: var(--max);
  margin: auto;
  padding: 0 24px;
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 2rem;
}

.brand { text-decoration: none; line-height: 1; }
.brand strong { display: block; font-size: 0.95rem; letter-spacing: -0.02em; }
.brand span { display: block; margin-top: 0.3rem; color: var(--muted); font: 0.64rem/1 var(--mono); text-transform: uppercase; letter-spacing: 0.12em; }

.primary-nav { display: flex; justify-content: center; gap: 1.5rem; }
.primary-nav a { color: var(--muted); text-decoration: none; font-size: 0.84rem; white-space: nowrap; }
.primary-nav a:hover, .primary-nav a[aria-current="page"] { color: var(--ink); }

.nav-actions { display: flex; gap: 0.35rem; }
.icon-button, .menu-button {
  width: 40px;
  height: 40px;
  display: inline-grid;
  place-items: center;
  border: 1px solid transparent;
  border-radius: var(--radius);
  background: transparent;
  cursor: pointer;
}
.icon-button:hover, .menu-button:hover { border-color: var(--line); background: var(--paper-2); }
.icon-button:active, .menu-button:active, .button:active { transform: translateY(1px); }
.menu-button { display: none; }

.hero {
  max-width: var(--max);
  min-height: calc(100dvh - 68px);
  margin: auto;
  padding: clamp(52px, 8vw, 96px) 24px;
  display: grid;
  grid-template-columns: minmax(0, 0.88fr) minmax(420px, 1.12fr);
  align-items: center;
  gap: clamp(3rem, 7vw, 7rem);
}

.eyebrow {
  margin: 0 0 1.4rem;
  color: var(--accent-dark);
  font: 0.72rem/1.3 var(--mono);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

h1, h2, h3 { text-wrap: balance; }
h1, h2 {
  margin: 0;
  font-family: var(--serif);
  font-weight: 500;
  letter-spacing: -0.035em;
}
h1 { max-width: 13ch; font-size: clamp(3.4rem, 6.4vw, 6.7rem); line-height: 0.94; }
h2 { font-size: clamp(2.25rem, 4vw, 4.5rem); line-height: 1.02; }
h3 { margin: 2.4rem 0 0.7rem; font-size: 1.15rem; line-height: 1.3; }
p { margin: 0 0 1.15rem; }

.hero-intro { max-width: 49ch; margin: var(--heading-copy-gap) 0 2rem; color: var(--muted); font-size: 1.05rem; line-height: 1.6; }
.hero-media { position: relative; min-width: 0; margin: 0; }
.hero-media img { width: 100%; min-height: 520px; object-fit: cover; box-shadow: var(--shadow); filter: saturate(0.9); }
.hero-caption { display: flex; justify-content: space-between; gap: 1rem; margin-top: 0.8rem; color: var(--muted); font: 0.68rem/1.45 var(--mono); }

.button-row { display: flex; flex-wrap: wrap; gap: 0.75rem; }
.button {
  display: inline-flex;
  min-height: 48px;
  align-items: center;
  justify-content: center;
  padding: 0.75rem 1.15rem;
  border: 1px solid var(--ink);
  border-radius: var(--radius);
  background: var(--ink);
  color: var(--paper);
  text-decoration: none;
  white-space: nowrap;
}
.button:hover { background: var(--accent-dark); border-color: var(--accent-dark); color: #fff8f3; }
.button.secondary { background: transparent; color: var(--ink); border-color: var(--line); }
.button.secondary:hover { border-color: var(--ink); }

.section { max-width: var(--max); margin: auto; padding: clamp(76px, 10vw, 140px) 24px; }
.section.compact { padding-top: 64px; padding-bottom: 64px; }
.section-heading { max-width: 780px; margin-bottom: 3.5rem; }
.section-heading p { max-width: 60ch; margin-top: var(--heading-copy-gap); color: var(--muted); }

.orientation-grid {
  display: grid;
  grid-template-columns: 1.3fr 0.7fr;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}
.orientation-main, .orientation-aside { background: var(--paper); padding: clamp(2rem, 5vw, 4.5rem); }
.orientation-main h2 + p { margin-top: var(--heading-copy-gap); }
.orientation-aside ol { margin: 0; padding: 0; list-style: none; counter-reset: item; }
.orientation-aside li { counter-increment: item; margin: 0 0 1.3rem; padding-left: 2.8rem; position: relative; }
.orientation-aside li::before { content: counter(item, decimal-leading-zero); position: absolute; left: 0; top: 0.1rem; color: var(--accent-dark); font: 0.72rem/1 var(--mono); }

.route-grid {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: 1px;
  border: 1px solid var(--line);
  background: var(--line);
}
.route-card {
  grid-column: span 4;
  min-height: 300px;
  padding: 2rem;
  display: flex;
  flex-direction: column;
  background: var(--paper);
  text-decoration: none;
  transition: background-color 180ms ease, color 180ms ease;
}
.route-card:nth-child(1), .route-card:nth-child(6) { grid-column: span 8; }
.route-card:nth-child(3), .route-card:nth-child(5) { background: var(--paper-2); }
.route-card:hover { background: var(--ink); color: var(--paper); }
.route-card .kicker { color: var(--accent-dark); font: 0.7rem/1.2 var(--mono); text-transform: uppercase; letter-spacing: 0.08em; }
.route-card h3 { margin: auto 0 1rem; font: 500 clamp(1.7rem, 3vw, 2.8rem)/1.05 var(--serif); }
.route-card p { max-width: 50ch; margin: 0; color: var(--muted); font-size: 0.9rem; }
.route-card:hover p, .route-card:hover .kicker { color: color-mix(in srgb, var(--paper) 75%, var(--accent)); }

.principles { display: grid; grid-template-columns: repeat(4, 1fr); gap: 2rem; }
.principle { padding-top: 1.4rem; border-top: 2px solid var(--ink); }
.principle strong { display: block; font: 500 1.45rem/1.2 var(--serif); }
.principle p { margin-top: 0.8rem; color: var(--muted); font-size: 0.9rem; }

.article-hero { max-width: var(--max); margin: auto; padding: clamp(70px, 10vw, 130px) 24px 64px; }
.article-hero h1 { max-width: 16ch; font-size: clamp(3.1rem, 6vw, 6rem); }
.article-deck { max-width: 64ch; margin: var(--heading-copy-gap) 0 2rem; color: var(--muted); font: 1.25rem/1.6 var(--serif); }
.article-meta { display: flex; flex-wrap: wrap; gap: 1.5rem; padding-top: 1.4rem; border-top: 1px solid var(--line); color: var(--muted); font: 0.72rem/1.4 var(--mono); }

.article-layout {
  max-width: var(--max);
  margin: auto;
  padding: 20px 24px 100px;
  display: grid;
  grid-template-columns: 220px minmax(0, var(--reading)) minmax(180px, 1fr);
  gap: clamp(2rem, 5vw, 5rem);
  align-items: start;
}
.toc { position: sticky; top: 100px; }
.toc strong { display: block; margin-bottom: 1rem; font: 0.7rem/1.3 var(--mono); text-transform: uppercase; letter-spacing: 0.08em; }
.toc a { display: block; padding: 0.4rem 0; color: var(--muted); font-size: 0.78rem; line-height: 1.35; text-decoration: none; }
.toc a:hover { color: var(--accent-dark); }

.prose { min-width: 0; }
.prose h2 { margin: 4.5rem 0 var(--heading-copy-gap); font-size: clamp(2rem, 3.7vw, 3.45rem); scroll-margin-top: 100px; }
.prose h2:first-child { margin-top: 0; }
.prose h3 { scroll-margin-top: 100px; }
.prose p, .prose li { max-width: 70ch; }
.prose p { font-family: var(--serif); font-size: 1.07rem; }
.prose a:not(.button) { color: var(--accent-dark); }
.prose sup a { font: 0.68rem var(--mono); text-decoration: none; }
.prose blockquote { margin: 2.6rem 0; padding: 0 0 0 1.7rem; border-left: 4px solid var(--accent); }
.prose blockquote p { font-size: 1.45rem; line-height: 1.42; }
.prose ul, .prose ol { padding-left: 1.25rem; }
.prose li { margin-bottom: 0.7rem; }

.concept-box, .example-box, .warning-box {
  margin: 2.5rem 0;
  padding: 1.7rem;
  border: 1px solid var(--line);
  background: var(--surface);
}
.example-box { border-left: 5px solid var(--accent); }
.warning-box { background: var(--paper-2); }
.box-title { display: block; margin-bottom: 0.8rem; font: 0.72rem/1.3 var(--mono); text-transform: uppercase; letter-spacing: 0.08em; }
.concept-box p:last-child, .example-box p:last-child, .warning-box p:last-child { margin-bottom: 0; }

.term { text-decoration: underline dotted var(--accent); text-underline-offset: 0.2em; cursor: help; }
.formula {
  margin: 2.5rem 0;
  padding: 2rem;
  overflow-x: auto;
  background: var(--ink);
  color: var(--paper);
  font: 1rem/1.8 var(--mono);
  white-space: nowrap;
}
.matrix { width: 100%; margin: 2.5rem 0; border-collapse: collapse; font-size: 0.9rem; }
.matrix th, .matrix td { padding: 1rem; border-bottom: 1px solid var(--line); text-align: left; vertical-align: top; }
.matrix th { color: var(--muted); font: 0.68rem/1.4 var(--mono); text-transform: uppercase; letter-spacing: 0.06em; }

.side-note { position: sticky; top: 100px; padding: 1.2rem; border-left: 1px solid var(--line); color: var(--muted); font-size: 0.78rem; }
.side-note strong { display: block; margin-bottom: 0.6rem; color: var(--ink); }

.chapter-nav { max-width: var(--max); margin: auto; padding: 0 24px 100px; display: grid; grid-template-columns: 1fr 1fr; gap: 1px; }
.chapter-nav a { min-height: 160px; padding: 2rem; border: 1px solid var(--line); text-decoration: none; }
.chapter-nav a + a { border-left: 0; text-align: right; }
.chapter-nav span { display: block; color: var(--muted); font: 0.68rem/1.4 var(--mono); text-transform: uppercase; letter-spacing: 0.08em; }
.chapter-nav strong { display: block; margin-top: 0.8rem; font: 500 1.5rem/1.2 var(--serif); }

.glossary-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 1px; background: var(--line); border: 1px solid var(--line); }
.glossary-entry { padding: 2rem; background: var(--paper); scroll-margin-top: 95px; }
.glossary-entry h2 { margin: 0 0 0.8rem; font-size: 1.8rem; }
.glossary-entry p { margin: 0; color: var(--muted); font-size: 0.92rem; }

.source-group { margin: 0 0 5rem; }
.source-group > h2 { margin-bottom: 2rem; }
.source-list { list-style: none; margin: 0; padding: 0; }
.source-item { display: grid; grid-template-columns: 140px 1fr auto; gap: 2rem; padding: 1.5rem 0; border-bottom: 1px solid var(--line); }
.source-type { color: var(--accent-dark); font: 0.68rem/1.4 var(--mono); text-transform: uppercase; }
.source-item strong { display: block; font: 500 1.08rem/1.35 var(--serif); }
.source-item p { margin: 0.4rem 0 0; color: var(--muted); font-size: 0.85rem; }
.source-link { align-self: center; font-size: 0.82rem; white-space: nowrap; }

.media-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 1.2rem; }
.media-card { border: 1px solid var(--line); background: var(--paper); text-decoration: none; }
.media-card img { width: 100%; aspect-ratio: 16/9; object-fit: cover; filter: saturate(0.7) contrast(1.05); }
.media-card-content { padding: 1.4rem; }
.media-card h3 { margin: 0 0 0.5rem; font: 500 1.4rem/1.2 var(--serif); }
.media-card p { margin: 0; color: var(--muted); font-size: 0.85rem; }

.quiz { margin: 3rem 0; border: 1px solid var(--line); }
.quiz-question { padding: 1.5rem; }
.quiz-question + .quiz-question { border-top: 1px solid var(--line); }
.quiz-question strong { display: block; margin-bottom: 1rem; }
.quiz label { display: block; padding: 0.45rem 0; cursor: pointer; }
.quiz-result { margin: 0; padding: 1.2rem 1.5rem; background: var(--paper-2); }

.site-footer { border-top: 1px solid var(--line); }
.footer-shell { max-width: var(--max); margin: auto; padding: 64px 24px; display: grid; grid-template-columns: 1fr 1fr 1fr; gap: 3rem; }
.footer-shell strong { font: 500 1.3rem/1.2 var(--serif); }
.footer-shell p, .footer-shell a { color: var(--muted); font-size: 0.8rem; }
.footer-links { display: grid; align-content: start; gap: 0.45rem; }

.search-panel { width: min(720px, calc(100vw - 32px)); padding: 0; border: 1px solid var(--line); background: var(--paper); color: var(--ink); box-shadow: var(--shadow); }
.search-panel::backdrop { background: rgba(20, 19, 17, 0.54); backdrop-filter: blur(4px); }
.search-head { display: flex; border-bottom: 1px solid var(--line); }
.search-head input { flex: 1; min-width: 0; padding: 1.1rem; border: 0; outline: 0; background: transparent; color: var(--ink); }
.search-results { max-height: 60vh; overflow: auto; padding: 0.7rem; }
.search-result { display: block; padding: 0.9rem; text-decoration: none; }
.search-result:hover { background: var(--paper-2); }
.search-result strong { display: block; }
.search-result span { color: var(--muted); font-size: 0.8rem; }
.search-empty { padding: 1rem; color: var(--muted); }

:focus-visible { outline: 3px solid color-mix(in srgb, var(--accent) 72%, transparent); outline-offset: 3px; }

@media (max-width: 1020px) {
  .primary-nav { display: none; position: absolute; top: 68px; left: 0; right: 0; padding: 1.2rem 24px 2rem; border-bottom: 1px solid var(--line); background: var(--paper); flex-direction: column; align-items: flex-start; }
  .primary-nav.open { display: flex; }
  .menu-button { display: inline-grid; }
  .nav-shell { grid-template-columns: 1fr auto; }
  .nav-actions { grid-column: 2; grid-row: 1; }
  .hero { grid-template-columns: 1fr 1fr; gap: 2.5rem; }
  .hero-media img { min-height: 420px; }
  .article-layout { grid-template-columns: 180px minmax(0, 1fr); }
  .side-note { display: none; }
  .principles { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 760px) {
  body { font-size: 16px; }
  .nav-shell { padding: 0 16px; }
  .brand span { display: none; }
  .nav-actions { gap: 0; }
  .icon-button, .menu-button { width: 36px; }
  .hero { min-height: auto; padding: 54px 16px 72px; grid-template-columns: 1fr; }
  .hero > * { min-width: 0; }
  .hero h1 { max-width: 100%; font-size: clamp(3rem, 15vw, 4.8rem); }
  .hero-media { order: -1; }
  .hero-media img { min-height: 300px; max-height: 48vh; }
  .hero-caption { display: block; }
  .hero-caption span:last-child { display: block; margin-top: 0.3rem; }
  .section { padding: 72px 16px; }
  .orientation-grid { grid-template-columns: 1fr; }
  .orientation-main, .orientation-aside { padding: 1.7rem; }
  .route-grid { grid-template-columns: 1fr; }
  .route-card, .route-card:nth-child(1), .route-card:nth-child(6) { grid-column: auto; min-height: 250px; }
  .principles { grid-template-columns: 1fr; }
  .article-hero { padding: 64px 16px 42px; }
  .article-hero h1 { font-size: clamp(2.8rem, 14vw, 4.2rem); }
  .article-layout { display: block; padding: 16px 16px 70px; }
  .toc { position: static; margin: 0 0 3rem; padding: 1rem; border: 1px solid var(--line); columns: 2; }
  .toc strong { column-span: all; }
  .prose h2 { margin-top: 3.5rem; }
  .chapter-nav { padding: 0 16px 72px; grid-template-columns: 1fr; }
  .chapter-nav a + a { border-left: 1px solid var(--line); border-top: 0; text-align: left; }
  .glossary-grid, .media-grid { grid-template-columns: 1fr; }
  .source-item { grid-template-columns: 1fr; gap: 0.5rem; }
  .source-link { margin-top: 0.5rem; }
  .footer-shell { grid-template-columns: 1fr; gap: 1.5rem; padding: 48px 16px; }
}

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

@media print {
  .site-header, .reading-progress, .toc, .side-note, .chapter-nav, .site-footer, .button-row { display: none !important; }
  body { background: #fff; color: #111; font-size: 11pt; }
  .article-hero, .article-layout { max-width: 100%; padding: 0; display: block; }
  .prose { max-width: 100%; }
  a { color: inherit; }
  a[href^="http"]::after { content: " (" attr(href) ")"; font-size: 8pt; overflow-wrap: anywhere; }
}