/* SDIT site-wide light theme and layout */
:root {
  --ink: #111;
  --bg: #fff;
  --muted: #666;
  --card: #f9f9f9;
  --border: #e0e0e0;
  --link: #0366d6;
  --highlight: #f3f4f6;
}
* { box-sizing: border-box; }
html { font-size: 16px; }
body {
  margin: 0;
  font-family: -apple-system, Segoe UI, Roboto, Inter, system-ui, sans-serif;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.65;
}

/* Header & Footer */
header.site-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 20px;
  border-bottom: 1px solid var(--border);
  background: var(--highlight);
  position: sticky;
  top: 0;
  z-index: 999;
}
header.site-header h1 { margin: 0; font-size: 24px; font-weight: 700; }
header.site-header nav a { margin-left: 20px; font-size: 16px; color: var(--link); text-decoration: none; }
header.site-header nav a:hover { text-decoration: underline; }

footer.site-footer {
  margin-top: 60px;
  text-align: center;
  padding: 30px;
  font-size: 14px;
  color: var(--muted);
  background: var(--highlight);
  border-top: 1px solid var(--border);
}

/* Main content */
main { padding: 40px 20px; max-width: 1100px; margin: 0 auto; }
.hero { text-align: center; margin-bottom: 40px; }
.hero h2 { font-size: 32px; margin-bottom: 10px; }
.hero p { font-size: 18px; color: var(--muted); margin-bottom: 20px; }
.hero .icon { font-size: 40px; margin-bottom: 10px; }
.cta-buttons { display: flex; justify-content: center; gap: 20px; flex-wrap: wrap; margin-bottom: 20px; }
.btn { display: inline-block; padding: 10px 20px; background: var(--link); color: #fff; border-radius: 8px; text-decoration: none; font-weight: 500; }
.btn:hover { opacity: 0.9; }

/* Search bar */
.search-bar { max-width: 420px; margin: 0 auto 24px; }
.search-bar input { width: 100%; padding: 10px; border: 1px solid var(--border); border-radius: 8px; font-size: 16px; }

/* Breadcrumbs */
.breadcrumbs { font-size: 14px; color: var(--muted); margin: 6px 0 16px; }
.breadcrumbs a { color: var(--muted); text-decoration: none; }
.breadcrumbs a:hover { text-decoration: underline; color: var(--ink); }
.breadcrumbs .sep { margin: 0 6px; color: var(--border); }

/* Cards and grids */
.card-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 20px; }
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 20px;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
}
.card h3 { margin: 8px 0 6px; font-size: 18px; }
.card .tagline, .card .desc { color: var(--muted); font-size: 14px; }
.subtitle { font-size: 14px; color: var(--muted); margin: 0 0 8px; }
.card .icon {
  margin-bottom: 8px;
  color: var(--link);
}
.card .icon svg {
  width: 24px;
  height: 24px;
}
.chapter-card .chapter-num { margin: 4px 0 8px; }
.card .card-actions { margin-top: 12px; display: flex; gap: 10px; }

/* Volume cards (home) */
.volume-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); gap: 20px; }
.volume-card { background: var(--card); border: 1px solid var(--border); border-radius: 10px; padding: 20px; text-align: center; }
.volume-card .icon {
  margin-bottom: 10px;
  color: var(--link);
}
.volume-card .icon svg {
  width: 36px;
  height: 36px;
}
.volume-card h3 { margin: 10px 0; font-size: 22px; font-weight: 700; }
.volume-card .tagline { color: var(--muted); font-size: 15px; margin: 0 0 8px; }
.volume-card .meta { color: var(--muted); font-size: 14px; margin-bottom: 12px; }
.volume-card .view-link { color: var(--link); text-decoration: none; font-weight: 500; }
.volume-card .view-link:hover { text-decoration: underline; }

/* Chapters and Sections as cards */
.cards-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 20px; }
.cards-grid .chapter-item, .cards-grid .section-item {
  list-style: none;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 20px;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
}
.cards-grid .chapter-item a, .cards-grid .section-item a { color: var(--link); text-decoration: none; font-weight: 600; }
.cards-grid .chapter-item a:hover, .cards-grid .section-item a:hover { text-decoration: underline; }
.cards-grid .section-meta { color: var(--muted); font-size: 14px; margin-top: 6px; }

/* Center chapter and section cards */
.card.chapter-card,
.cards-grid .chapter-item,
.cards-grid .section-item {
  text-align: center;
}

@media (max-width: 768px) {
  main { padding: 20px 16px; }
  header.site-header { flex-direction: column; align-items: flex-start; }
  header.site-header nav { margin-top: 10px; }
  header.site-header h1 { font-size: 22px; }
  .hero h2 { font-size: 26px; }
  .hero p { font-size: 16px; }
}