:root { --prose-width: 740px; }


/* ─── Index page ─────────────────────────────────────────────────────────── */
.paper-label {
  display: block;
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: .1em;
  font-weight: 800;
  color: var(--muted);
  margin: 28px 0 12px;
}
.notes-grid {
  max-width: 1280px;
  margin: 0 auto;
  padding: 24px 28px 48px;
}
.unit-card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  margin-bottom: 16px;
  overflow: hidden;
}
.unit-card-head {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 16px 20px;
  background: linear-gradient(180deg, #fafbfc, var(--surface));
  border-bottom: 1px solid var(--line);
}
.unit-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 36px;
  height: 36px;
  border-radius: 9px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 11px;
  font-weight: 800;
  letter-spacing: .02em;
  flex-shrink: 0;
}
.unit-card-head h2 {
  font-size: 15px;
  font-weight: 700;
  letter-spacing: -.01em;
  margin: 0;
  flex: 1;
}
.unit-formula-link {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 5px 11px;
  border-radius: 999px;
  font-size: 11px;
  font-weight: 700;
  text-decoration: none;
  transition: all .15s;
  white-space: nowrap;
  border: 1px solid #e5c87a;
  background: #fffbea;
  color: #9a6f0a;
}
.unit-formula-link:hover { background: #fef3c0; border-color: #d4a017; color: #7a5500; }
.unit-formula-link svg { width: 12px; height: 12px; fill: none; stroke: currentColor; stroke-width: 2; }
.unit-formula-link.disabled, a.disabled {
  pointer-events: none;
  opacity: .38;
  cursor: default;
}
.unit-sections {
  display: flex;
  flex-direction: column;
  padding: 6px 0;
}
.section-row {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 20px;
  border-bottom: 1px solid #f0f2f5;
  transition: background .12s;
}
.section-row:last-child { border-bottom: none; }
.section-row:hover:not(.disabled-row) { background: #f8f9fb; }
.section-code-badge {
  font-size: 9.5px;
  font-weight: 800;
  color: #7b848e;
  background: var(--surface-2);
  border: 1px solid var(--line);
  border-radius: 5px;
  padding: 2px 6px;
  flex-shrink: 0;
}
.section-link {
  flex: 1;
  font-size: 13.5px;
  font-weight: 500;
  color: var(--accent);
  text-decoration: none;
  transition: color .12s;
}
.section-link:hover { color: #1e3aaa; text-decoration: underline; }
.section-link.disabled-link {
  pointer-events: none;
  color: var(--muted);
  opacity: .45;
}
.coming-soon-chip {
  font-size: 9px;
  font-weight: 700;
  letter-spacing: .06em;
  color: #94a3b8;
  background: #f1f5f9;
  border: 1px solid #e2e8f0;
  border-radius: 999px;
  padding: 2px 7px;
  white-space: nowrap;
}

/* ─── Viewer page ─────────────────────────────────────────────────────────── */
.viewer-layout {
  max-width: 1280px;
  margin: 0 auto;
  padding: 28px 28px 64px;
  display: grid;
  grid-template-columns: var(--prose-width) 1fr;
  gap: 32px;
  align-items: start;
}
.viewer-main { min-width: 0; }

/* Breadcrumb */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
  color: var(--muted);
  margin-bottom: 20px;
  flex-wrap: wrap;
}
.breadcrumb a { color: var(--accent); text-decoration: none; font-weight: 600; }
.breadcrumb a:hover { text-decoration: underline;  }
.breadcrumb-sep { color: #aab0b8; font-size: 11px; }

/* Prose content card */
.prose-card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 36px 44px;
}

/* Prose typography */
.prose {
  font-family: 'Source Serif 4', Georgia, serif;
  font-size: 16px;
  line-height: 1.75;
  color: var(--text);
}
.prose h1 { font-size: 24px; letter-spacing: -.03em; margin: 0 0 4px; line-height: 1.2; }
.prose h2 { font-size: 18px; font-weight: 700; letter-spacing: -.02em; margin: 2em 0 .6em; border-bottom: 1px solid var(--line); padding-bottom: .3em; }
.prose h3 { font-size: 15px; font-weight: 700; margin: 1.5em 0 .4em; }
.prose p  { margin: .3em 0 .85em; }
.prose ul, .prose ol { margin: .4em 0 .85em; padding-left: 1.5em; }
.prose li { margin: .25em 0; }
.prose strong { font-weight: 700; color: #1a2536; }
.prose em { font-style: italic; }
.prose code {
  font-family: 'JetBrains Mono', 'Fira Code', monospace;
  font-size: .87em;
  background: var(--surface-2);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: .1em .4em;
}
.prose pre { background: #1e2533; border-radius: 9px; padding: 18px 22px; overflow-x: auto; margin: 1em 0 1.2em; }
.prose pre code { background: none; border: none; color: #e2e8f0; font-size: .9em; padding: 0; }
.prose blockquote { margin: 1em 0; padding: .6em 1em; border-left: 3px solid var(--accent); background: var(--accent-soft); border-radius: 0 8px 8px 0; color: #2e4090; font-style: normal; }
.prose hr { border: none; border-top: 1px solid var(--line); margin: 2em 0; }

/* Tables */
.prose table { width: 100%; border-collapse: collapse; margin: 1em 0 1.4em; font-size: 14.5px; font-family: Inter, system-ui, sans-serif; }
.prose th { background: #fafbfc; font-weight: 700; font-size: 11px; text-transform: uppercase; letter-spacing: .06em; color: #7b848e; padding: 9px 14px; border: 1px solid var(--line); text-align: left; }
.prose td { padding: 9px 14px; border: 1px solid var(--line); vertical-align: middle; }
.prose tr:nth-child(even) td { background: #fafbfc; }

/* KaTeX */
.prose .katex-display { overflow-x: auto; padding: .5em 0; margin: .8em 0 1em; }
.prose .katex { font-size: 1.05em; }

/* GitHub-style alert blockquotes */
.prose blockquote.alert-note    { border-left-color: #3b82f6; background: #eff6ff; color: #1e40af; }
.prose blockquote.alert-tip     { border-left-color: #22c55e; background: #f0fdf4; color: #166534; }
.prose blockquote.alert-important { border-left-color: #8b5cf6; background: #f5f3ff; color: #5b21b6; }
.prose blockquote.alert-warning { border-left-color: #f59e0b; background: #fffbeb; color: #92400e; }
.prose blockquote.alert-caution { border-left-color: #ef4444; background: #fef2f2; color: #991b1b; }

/* ─── Right sidebar ─────────────────────────────────────────────────────── */
.viewer-sidebar { position: sticky; top: 24px; }
.sidebar-card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow: hidden;
  margin-bottom: 14px;
}
.sidebar-head {
  padding: 11px 14px;
  background: #fafbfc;
  border-bottom: 1px solid var(--line);
  font-size: 10px;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: .1em;
  color: var(--muted);
}
.sidebar-body { padding: 12px 14px; }

/* Print button in sidebar */
.print-note-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  width: 100%;
  padding: 10px 16px;
  border: none;
  border-radius: 9px;
  background: var(--accent);
  color: #fff;
  font: inherit;
  font-size: 13px;
  font-weight: 700;
  cursor: pointer;
  box-shadow: 0 3px 10px rgba(49,87,213,.2);
  transition: background .15s, transform .15s, box-shadow .15s;
}
.print-note-btn:hover { background: #2749b8; transform: translateY(-1px); box-shadow: 0 5px 14px rgba(49,87,213,.25); }
.print-note-btn:active { transform: translateY(0); }
.print-note-btn svg { width: 16px; height: 16px; fill: none; stroke: currentColor; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }

/* Prev/Next nav */
.nav-prev-next {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 10px 14px;
}
.nav-note-btn {
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 8px 11px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  color: var(--text);
  font: inherit;
  font-size: 12px;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  transition: all .15s;
}
.nav-note-btn:hover { border-color: var(--accent); color: var(--accent); background: var(--accent-soft); }
.nav-note-btn.disabled { pointer-events: none; opacity: .35; }
.nav-note-btn svg { width: 13px; height: 13px; fill: none; stroke: currentColor; stroke-width: 2.5; flex-shrink: 0; }
.nav-note-label { font-size: 9px; color: var(--muted); display: block; font-weight: 700; text-transform: uppercase; letter-spacing: .07em; margin-bottom: 1px; }

/* Loading / error states */
.prose-loading {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 14px;
  min-height: 300px;
  color: var(--muted);
  font-size: 14px;
}
.prose-spinner {
  width: 28px; height: 28px;
  border: 3px solid var(--line);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin .8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }
.prose-error {
  padding: 24px;
  border: 1px solid #fecaca;
  border-radius: 9px;
  background: #fef2f2;
  color: #991b1b;
  font-size: 13px;
  text-align: center;
}

/* sr-only */
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; }

/* ─── Responsive ─────────────────────────────────────────────────────────── */
@media (max-width: 900px) {
  .viewer-layout { grid-template-columns: 1fr; }
  .viewer-sidebar { position: static; }
  .nav-prev-next { flex-direction: row; flex-wrap: wrap; }
  .notes-grid { padding: 16px 14px 40px; }
  .prose-card { padding: 24px 20px; }
}
@media (max-width: 560px) {
  .viewer-layout { padding: 16px 12px 48px; }
  .prose { font-size: 15px; }
}

/* ─── Print styles ─────────────────────────────────────────────────────────
   Goal: print ONLY the prose content + equations on clean A4 paper.
   • Hide all nav, sidebar, breadcrumb, buttons.
   • Add a right margin (blank space + vertical bar separator).
   • Preserve KaTeX equations (they are inline SVG/HTML — print-safe).
   • Auto-set document title via @page.
─────────────────────────────────────────────────────────────────────────── */
@media print {
  @page {
    size: A4;
    /* Top/bottom generous; left normal; right wide for the margin bar */
    margin: 18mm 18mm 18mm 18mm;
  }

  /* Hide everything except the prose card */
  body > *:not(.viewer-layout) { display: none !important; }
  .site-nav,
  .breadcrumb,
  .viewer-sidebar { display: none !important; }
  .viewer-layout {
    display: block !important;
    max-width: 100%;
    padding: 0;
  }
  .prose-card {
    border: none !important;
    box-shadow: none !important;
    padding: 0 !important;
  }

  /* Right margin bar — a thin vertical rule printed in the wide right margin */
  .viewer-main::after {
    content: "";
    position: fixed;
    top: 0;
    bottom: 0;
    right: 75mm;   /* sits just inside the 80mm right margin */
    width: 1px;
    background: #0e0d0d;
  }

  /* Prose print tweaks */
  .prose {
    font-size: 11pt;
    line-height: 1.55;
    color: #111;
  }
  .prose h1 { font-size: 17pt; }
  .prose h2 { font-size: 13pt; border-bottom-color: #ccc; }
  .prose h3 { font-size: 11.5pt; }
  .prose table, .prose th, .prose td { border-color: #ccc !important; }
  .prose blockquote { border-left-color: #aaa !important; background: #f8f8f8 !important; color: #333 !important; }
  .prose pre { background: #f4f4f4 !important; }
  .prose pre code { color: #222 !important; }

  /* KaTeX in print: force display math to stay on page */
  .katex-display { page-break-inside: avoid; }

  /* Page break control */
  h2, h3 { page-break-after: avoid; }
  table, blockquote { page-break-inside: avoid; }
}

/* ─── Notes Lander Footer ─────────────────────────────────────────────────── */
.notes-grid + .site-footer {
  max-width: 1280px;
  margin: 16px auto 0;
  padding: 0 28px 40px;
}
@media (max-width: 768px) {
  .notes-grid + .site-footer {
    padding: 0 16px 28px;
    margin-top: 8px;
  }
}