/* Base */
:root { --bg: #ffffff; --fg: #111; --muted: #555; --line: #e6e6e6; --accent: #111; --card: #fafafa; }
html[data-theme="dark"] { --bg: #0b0b0b; --fg: #f5f5f5; --muted: #b5b5b5; --line: #1f1f1f; --accent: #f5f5f5; --card: #121212; }
* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0; background: var(--bg); color: var(--fg);
  font-family: "Noto Sans", system-ui, -apple-system, Segoe UI, Roboto, Arial, sans-serif;
  line-height: 1.6;
}

/* Header */
.site-header {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; justify-content: space-between;
  gap: 1rem; padding: .75rem 1rem; border-bottom: 1px solid var(--line);
  background: color-mix(in oklab, var(--bg) 90%, transparent);
  backdrop-filter: saturate(120%) blur(8px);
}
.logo { width: 240px; height: 36px; fill: var(--fg); }
.header-actions { display: flex; gap: .5rem; align-items: center; }
.search input {
  border: 1px solid var(--line); background: var(--bg); color: var(--fg);
  padding: .5rem .75rem; border-radius: 8px; min-width: 280px;
}
.btn, .btn-sm, .linklike {
  border: 1px solid var(--line); background: var(--bg); color: var(--fg);
  padding: .5rem .75rem; border-radius: 8px; cursor: pointer;
}
.btn-sm { padding: .25rem .5rem; font-size: .9rem; }
.linklike { background: none; border: none; color: var(--muted); padding: 0; }
.linklike:hover { color: var(--fg); text-decoration: underline; }

/* Layout */
.layout { display: grid; grid-template-columns: 280px 1fr; gap: 2rem; max-width: 1200px; margin: 0 auto; padding: 1.5rem; }
.toc { position: sticky; top: 64px; align-self: start; border-right: 1px solid var(--line); padding-right: 1rem; }
.toc ol { list-style: none; margin: 0; padding: 0; }
.toc a { display: block; padding: .35rem 0; color: var(--muted); text-decoration: none; }
.toc a.active { color: var(--fg); font-weight: 700; }
.quick-actions { margin-top: 1rem; display: flex; gap: .75rem; flex-wrap: wrap; }

.content { min-width: 0; }
.block { padding: 1rem 0 1.5rem; border-bottom: 1px solid var(--line); }
h1, h2 { line-height: 1.25; margin: .5rem 0 1rem; }
h1 { font-size: clamp(1.6rem, 2.4vw + 1rem, 2.2rem); }
h2 { font-size: clamp(1.2rem, 1.6vw + 1rem, 1.6rem); }
h3 { margin: .75rem 0 .25rem; font-size: 1.05rem; }
p, li { color: var(--fg); }
.note { border: 1px dashed var(--line); padding: .75rem; border-radius: 8px; color: var(--muted); }

.key-points { display: grid; grid-template-columns: repeat(2,1fr); gap: 1rem; }
.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 1rem; }
.card {
  border: 1px solid var(--line); background: var(--card); border-radius: 12px; padding: 1rem;
  transition: transform .15s ease;
}
.card:hover { transform: translateY(-2px); }

/* Accordion */
.accordion .item { border: 1px solid var(--line); border-radius: 10px; margin-bottom: .75rem; background: var(--card); }
.accordion button.header {
  width: 100%; text-align: left; padding: .9rem 1rem; background: none; border: none; color: var(--fg);
  display: flex; justify-content: space-between; align-items: center; font-weight: 700; cursor: pointer;
}
.accordion .panel { padding: 0 1rem 1rem; display: none; }
.accordion .item[aria-expanded="true"] .panel { display: block; }
.chev { transition: transform .15s ease; }
.item[aria-expanded="true"] .chev { transform: rotate(90deg); }

/* Chapters */
.chapters { display: grid; gap: .75rem; padding-left: 1rem; }
.chapters li { background: var(--card); border: 1px solid var(--line); border-radius: 10px; padding: .75rem; }

/* Glossary */
.glossary { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: .75rem; }
.glossary li { border: 1px solid var(--line); background: var(--card); border-radius: 10px; padding: .75rem; }
.glossary-term { font-weight: 700; }
mark.gloss { background: #ffe58a; color: var(--fg); padding: 0 .2em; border-radius: 3px; }

/* Resources and notes */
.resources { padding-left: 1rem; }
#notesArea {
  width: 100%; border: 1px solid var(--line); background: var(--bg); color: var(--fg);
  border-radius: 10px; padding: .75rem; font-family: inherit;
}
.note-actions { display: flex; align-items: center; gap: .5rem; margin-top: .5rem; }

/* Footer */
.site-footer { border-top: 1px solid var(--line); padding: 1rem; text-align: center; color: var(--muted); }

/* Utilities and accessibility */
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0,0,0,0); border: 0; }
[hidden] { display: none !important; }
.highlight { outline: 2px dashed var(--line); outline-offset: 2px; }

/* Responsive */
@media (max-width: 960px) {
  .layout { grid-template-columns: 1fr; }
  .toc { position: static; border-right: none; padding-right: 0; }
  .search input { min-width: 180px; width: 50vw; }
  .key-points { grid-template-columns: 1fr; }
}

/* Print */
@media print {
  .site-header, .toc, .quick-actions, .note-actions, #themeToggle { display: none !important; }
  body { background: #fff; color: #000; }
  .block { break-inside: avoid; }
}