:root {
  --ink: #1c2b33;
  --ink-soft: #4a5a63;
  --paper: #f6f4ee;
  --paper-raised: #ffffff;
  --line: #d8d3c4;
  --accent: #2f6f5e;
  --accent-ink: #ffffff;
  --amber: #b5762c;
  --radius: 8px;
  --font-body: "Iowan Old Style", "Georgia", serif;
  --font-ui: -apple-system, "Segoe UI", Roboto, sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root {
    --ink: #ecebe5;
    --ink-soft: #b7b3a6;
    --paper: #16201f;
    --paper-raised: #1e2a29;
    --line: #34433f;
    --accent: #6fbfa4;
    --accent-ink: #0d1a17;
    --amber: #d99a4e;
  }
}

* { box-sizing: border-box; }
html { height: 100%; }
body {
  margin: 0;
  min-height: 100%;
  display: flex;
  flex-direction: column;
  font-family: var(--font-ui);
  background: var(--paper);
  color: var(--ink);
  line-height: 1.5;
}
a { color: var(--accent); }
.hidden { display: none !important; }

/* Header */
.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 24px;
  border-bottom: 1px solid var(--line);
  background: var(--paper-raised);
}
.brand { display: flex; align-items: baseline; gap: 10px; }
.brand h1 { font-family: var(--font-body); font-size: 22px; margin: 0; letter-spacing: 0.2px; }
.brand span { font-size: 13px; color: var(--ink-soft); }
#main-nav-items { display: flex; align-items: center; gap: 20px; }
.nav-link { text-decoration: none; color: var(--ink); font-size: 14px; }
.nav-link:hover { color: var(--accent); }
.nav-cta {
  background: var(--accent);
  color: var(--accent-ink);
  border: none;
  padding: 8px 16px;
  border-radius: var(--radius);
  font-size: 14px;
  cursor: pointer;
}

/* Announcement */
.announcement-bar {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  background: #eae3d0;
  color: #4a3a1c;
  padding: 8px 16px;
  font-size: 13px;
}
.announcement-dismiss { background: none; border: none; cursor: pointer; font-size: 13px; color: inherit; }

/* Layout */
main { max-width: 980px; margin: 0 auto; padding: 32px 24px; width: 100%; box-sizing: border-box; flex: 1; }

.home-hero { margin-bottom: 40px; }
.home-hero h1 { font-family: var(--font-body); font-size: 28px; margin: 0 0 8px; }
.home-hero p { color: var(--ink-soft); font-size: 15px; max-width: 620px; margin: 0 0 20px; }
.hero-steps {
  list-style: none;
  counter-reset: step;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 12px;
  margin: 0 0 20px;
  padding: 0;
}
.hero-steps li {
  counter-increment: step;
  background: var(--paper-raised);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 12px 14px;
  font-size: 13px;
  position: relative;
  padding-left: 34px;
}
.hero-steps li::before {
  content: counter(step);
  position: absolute;
  left: 10px;
  top: 12px;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--accent);
  color: var(--accent-ink);
  font-size: 11px;
  display: flex;
  align-items: center;
  justify-content: center;
}
.btn-primary {
  display: inline-block;
  background: var(--accent);
  color: var(--accent-ink);
  border: none;
  padding: 10px 18px;
  border-radius: var(--radius);
  font-size: 14px;
  text-decoration: none;
  margin-bottom: 24px;
}
.department-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 10px;
}
.dept-card {
  display: flex;
  align-items: center;
  gap: 8px;
  background: var(--paper-raised);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 12px 14px;
  font-size: 14px;
  color: var(--ink);
  cursor: pointer;
  text-align: left;
}
.dept-card:hover { border-color: var(--accent); color: var(--accent); }
.dept-card i { font-size: 18px; color: var(--accent); }

.controls-row { display: flex; gap: 12px; flex-wrap: wrap; margin-bottom: 24px; }
select, input[type="text"] {
  padding: 9px 12px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--paper-raised);
  color: var(--ink);
  font-size: 14px;
  min-width: 220px;
}
#search-input { flex: 1; min-width: 200px; }

/* File list */
.file-row {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 12px 14px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  margin-bottom: 8px;
  background: var(--paper-raised);
}
.file-icon { font-size: 22px; color: var(--accent); }
.file-meta { flex: 1; display: flex; flex-direction: column; }
.file-name { font-size: 14px; }
.file-sub { font-size: 12px; color: var(--ink-soft); }
.file-actions { display: flex; gap: 6px; }
.btn-icon {
  border: 1px solid var(--line);
  background: var(--paper-raised);
  color: var(--ink);
  border-radius: 6px;
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  text-decoration: none;
}
.btn-icon:hover { border-color: var(--accent); color: var(--accent); }
.empty-state { text-align: center; color: var(--ink-soft); padding: 40px 0; }

/* Preview modal */
.modal-overlay {
  position: fixed; inset: 0;
  background: rgba(0,0,0,0.55);
  display: flex; align-items: center; justify-content: center;
  z-index: 50;
}
.modal-panel {
  background: var(--paper-raised);
  border-radius: var(--radius);
  width: min(900px, 92vw);
  height: min(680px, 88vh);
  display: flex; flex-direction: column;
  overflow: hidden;
}
.modal-header { display: flex; align-items: center; justify-content: space-between; padding: 12px 16px; border-bottom: 1px solid var(--line); }
.modal-body { flex: 1; overflow: auto; padding: 12px; }
.preview-frame { width: 100%; height: 100%; border: none; }
.preview-image, .preview-media { max-width: 100%; max-height: 100%; display: block; margin: 0 auto; }
.preview-markdown { padding: 12px; font-family: var(--font-body); }
.preview-fallback-note { font-size: 12px; color: var(--ink-soft); padding: 8px; }

/* Lecture mode */
.lecture-overlay {
  position: fixed; inset: 0;
  background: #10171a;
  z-index: 100;
  display: flex; flex-direction: column;
}
.lecture-topbar { display: flex; align-items: center; justify-content: space-between; padding: 10px 18px; color: #e8e6de; }
.lecture-stage { flex: 1; display: flex; align-items: center; justify-content: center; }
.lecture-frame, .lecture-image { width: 100%; height: 100%; border: none; object-fit: contain; }
.lecture-bottombar { display: flex; align-items: center; justify-content: center; gap: 16px; padding: 12px; color: #e8e6de; }
.lecture-bottombar button { background: #26332f; color: #e8e6de; border: none; border-radius: 6px; padding: 8px 14px; cursor: pointer; }
.lecture-bottombar button:disabled { opacity: 0.4; cursor: default; }
#lecture-qr { background: #fff; padding: 8px; border-radius: 6px; }
.bookmark-chip { background: #26332f; color: #e8e6de; border: none; border-radius: 12px; padding: 4px 10px; font-size: 12px; cursor: pointer; }
.bookmark-chip:hover { background: var(--accent); }

/* Consent banner */
.consent-banner {
  position: fixed; left: 16px; right: 16px; bottom: 16px;
  background: var(--paper-raised);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px;
  display: flex; align-items: center; gap: 16px; flex-wrap: wrap;
  z-index: 80;
  max-width: 640px;
  margin: 0 auto;
}
.consent-banner p { margin: 0; font-size: 13px; flex: 1; min-width: 200px; }
.consent-banner button { border-radius: 6px; padding: 8px 14px; font-size: 13px; cursor: pointer; }
#consent-learn-more { font-size: 13px; white-space: nowrap; }
.ad-slot { margin: 24px 0; text-align: center; min-height: 0; }
.ad-slot.hidden { display: none; }
#consent-accept { background: var(--accent); color: var(--accent-ink); border: none; }
#consent-decline { background: none; border: 1px solid var(--line); color: var(--ink); }

/* Footer */
.site-footer { border-top: 1px solid var(--line); padding: 18px 24px; display: flex; justify-content: space-between; flex-wrap: wrap; gap: 8px; font-size: 12px; color: var(--ink-soft); }
#footer-links a { color: var(--ink-soft); margin-left: 12px; text-decoration: none; }
#footer-links a:hover { color: var(--accent); }

@media (max-width: 640px) {
  .site-header { flex-direction: column; align-items: flex-start; gap: 10px; }
  #main-nav-items { flex-wrap: wrap; }
}