/* Geotechnical route: survey navy, strata stone, brass and safety yellow. */
body.book-yt {
  --ink: #24313a;
  --muted: #68747b;
  --line: #d5dfe0;
  --paper: #fcfdfb;
  --mist: #edf3f3;
  --brand: #185b68;
  --brand-strong: #0f3f4b;
  --brand-soft: #dbecee;
  --accent: #b8752d;
  --accent-soft: #f9ead4;
  --blue: #3d718a;
  --blue-soft: #e2eef2;
  --shadow: 0 18px 46px rgba(15, 63, 75, 0.15);
  --stage: #172d36;
  --stage-ink: #f6f7ef;
  --stage-muted: rgba(246, 247, 239, 0.72);
  --stage-line: rgba(246, 247, 239, 0.2);
  --stage-accent: #d7ad54;
  --stage-acid: #b8d4c3;
  --stage-secondary: #d18b35;
  --stage-surface: #fcfdfb;
  --stage-surface-strong: #e7f0ee;
  --stage-surface-line: #d5dfe0;
  background: #edf3f3;
}

body.book-yt::before {
  background:
    repeating-linear-gradient(90deg, rgba(24, 91, 104, 0.05) 0 1px, transparent 1px 58px),
    repeating-linear-gradient(0deg, rgba(184, 117, 45, 0.035) 0 1px, transparent 1px 58px);
  opacity: 0.78;
}

body.book-yt .brand-mark {
  color: #dfb35e;
  border-color: #dfb35e;
  box-shadow: 5px 5px 0 #c46f2d;
}

body.book-yt .hero-band::before { content: "GEOTECH / 23"; }
body.book-yt .hero-band::after {
  content: "岩";
  color: transparent;
  -webkit-text-stroke-color: rgba(215, 173, 84, 0.23);
  font-family: "Microsoft YaHei", sans-serif;
}

body.book-yt .book-preview::after { content: "SOURCE / 10P"; }
body.book-yt .hero-band .primary-button,
body.book-yt .primary-button { box-shadow: 5px 5px 0 #c46f2d; }
body.book-yt .hero-band .primary-button:hover,
body.book-yt .primary-button:hover { box-shadow: 1px 1px 0 #c46f2d; }
body.book-yt .stat::before,
body.book-yt .course-item::before,
body.book-yt .practice-item::before,
body.book-yt .paper-card::before,
body.book-yt .progress-bar span,
body.book-yt .quiz-meter span { background: #c46f2d; }
body.book-yt .section:nth-of-type(odd) { background: rgba(255, 255, 255, 0.68); }

@media (max-width: 720px) {
  body.book-yt .hero-band::after { font-size: 180px; }
}