:root {
  color-scheme: light dark;
  --bg: #f7f6f3;
  --card: #ffffff;
  --text: #1d1d1f;
  --text-dim: #6b6b76;
  --border: #e5e3dd;
  --accent: #4f6df5;
  --genius: #eef1ff;
  --genius-border: #c9d3ff;
  --kid: #fff4e8;
  --kid-border: #ffdca8;
  --term-bg: #fff3c4;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f0f13;
    --card: #17171d;
    --text: #f0f0f2;
    --text-dim: #92929c;
    --border: #2a2a32;
    --genius: #1a2040;
    --genius-border: #33407a;
    --kid: #332816;
    --kid-border: #6b5227;
    --term-bg: #4a3d10;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Pretendard, Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.65;
}
.topnav {
  position: sticky;
  top: 0;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  z-index: 10;
}
.topnav-inner {
  max-width: 780px;
  margin: 0 auto;
  padding: 12px 20px;
  display: flex;
  align-items: center;
  gap: 14px;
  overflow-x: auto;
  white-space: nowrap;
}
.topnav a {
  color: var(--text-dim);
  text-decoration: none;
  font-size: 0.82rem;
  padding: 5px 10px;
  border-radius: 999px;
}
.topnav a.brand {
  color: var(--text);
  font-weight: 700;
  font-size: 0.92rem;
  padding-right: 6px;
}
.topnav a.active, .topnav a:hover { background: var(--genius); color: var(--accent); }

main {
  max-width: 720px;
  margin: 0 auto;
  padding: 16px 16px 60px;
}
h1.page-title { font-size: 1.4rem; margin: 0 0 4px; }
.page-sub { color: var(--text-dim); font-size: 0.88rem; margin: 0 0 18px; }

.bubble {
  display: flex;
  gap: 8px;
  margin-bottom: 4px;
  align-items: baseline;
  padding: 5px 0 5px 10px;
  border-left: 3px solid transparent;
}
.bubble .avatar { display: none; }
.bubble .msg {
  font-size: 1.02rem;
  line-height: 1.7;
}
.bubble.genius { border-left-color: var(--genius-border); }
.bubble.kid { border-left-color: var(--kid-border); }
.speaker {
  display: inline;
  font-size: 0.85rem;
  color: var(--text-dim);
  font-weight: 700;
  margin-right: 4px;
}
.speaker::after { content: ":"; }

.term {
  background: var(--term-bg);
  padding: 0 4px;
  border-radius: 4px;
  text-decoration: none;
  color: inherit;
  font-weight: 600;
  border-bottom: 1px dashed var(--text-dim);
}
.term:hover { filter: brightness(1.1); }

.callout {
  background: var(--card);
  border: 1px solid var(--border);
  border-left: 4px solid var(--accent);
  border-radius: 8px;
  padding: 10px 14px;
  margin: 12px 0;
  font-size: 0.92rem;
  line-height: 1.6;
}
.callout .callout-title { font-weight: 700; margin-bottom: 4px; }

pre {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 12px 14px;
  overflow-x: auto;
  font-size: 0.85rem;
}
code { font-family: "SF Mono", Menlo, Consolas, monospace; }

.chapter-nav {
  display: flex;
  justify-content: space-between;
  margin-top: 24px;
  padding-top: 14px;
  border-top: 1px solid var(--border);
  font-size: 0.85rem;
}
.chapter-nav a { color: var(--accent); text-decoration: none; }
.chapter-nav a:hover { text-decoration: underline; }

.glossary-entry {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px 18px;
  margin-bottom: 12px;
  scroll-margin-top: 70px;
}
.glossary-entry h3 { margin: 0 0 6px; font-size: 1.02rem; }
.glossary-entry p { margin: 0; font-size: 0.9rem; color: var(--text-dim); }
.glossary-entry .glossary-tag {
  font-size: 0.7rem;
  color: var(--accent);
  background: var(--genius);
  border-radius: 999px;
  padding: 1px 8px;
  margin-left: 8px;
}

.toc-list { list-style: none; padding: 0; margin: 0; display: flex; flex-direction: column; gap: 8px; }
.toc-list a {
  display: block;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px 16px;
  color: var(--text);
  text-decoration: none;
}
.toc-list a:hover { border-color: var(--accent); }
.toc-num { color: var(--accent); font-weight: 700; margin-right: 8px; }
.toc-desc { display: block; color: var(--text-dim); font-size: 0.85rem; margin-top: 3px; }