:root {
  --bg: #fbfaf7; --fg: #1d1d1f; --muted: #6b6b70; --line: #e4e1da; --card: #ffffff;
  --accent: #c2410c; --news: #0f766e; --paper: #6d28d9; --lecture: #b45309;
  --serif: "Iowan Old Style", "Palatino Linotype", Georgia, serif;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}
@media (prefers-color-scheme: dark) {
  :root { --bg: #121214; --fg: #ececee; --muted: #9a9aa2; --line: #2a2a2f; --card: #1a1a1d;
    --accent: #fb923c; --news: #2dd4bf; --paper: #a78bfa; --lecture: #fbbf24; }
}
* { box-sizing: border-box; }
body { margin: 0; background: var(--bg); color: var(--fg); font: 17px/1.6 var(--sans); }
a { color: inherit; text-underline-offset: 3px; }
main, .top, .foot { max-width: 980px; margin: 0 auto; padding: 0 16px; }
.top { display: flex; justify-content: space-between; align-items: center; padding-top: 18px; padding-bottom: 18px; border-bottom: 1px solid var(--line); }
.brand { font-weight: 700; text-decoration: none; letter-spacing: -0.01em; }
.brand span { color: var(--muted); font-weight: 400; }
.langs a { margin-left: 14px; color: var(--muted); font-size: 15px; }
.intro h1 { font: 700 clamp(28px, 5vw, 44px)/1.15 var(--serif); margin: 36px 0 8px; }
.intro p { color: var(--muted); margin: 0 0 24px; }
.sections { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 8px; }
.sections a, .levels button { border: 1px solid var(--line); background: var(--card); color: var(--fg); padding: 6px 14px; border-radius: 999px; text-decoration: none; font: 15px var(--sans); cursor: pointer; }
.sections a[aria-current], .levels button[aria-selected="true"] { background: var(--fg); color: var(--bg); border-color: var(--fg); }
.day h2 { font: 600 14px var(--sans); text-transform: uppercase; letter-spacing: 0.06em; color: var(--muted); margin: 32px 0 12px; }
.card { background: var(--card); border: 1px solid var(--line); border-radius: 12px; padding: 16px 18px; margin-bottom: 12px; }
.card h3 { font: 600 21px/1.3 var(--serif); margin: 6px 0; }
.card h3 a { text-decoration: none; }
.card h3 a:hover { text-decoration: underline; }
.card p { margin: 0; color: var(--muted); }
.meta { font-size: 14px; color: var(--muted); display: flex; gap: 10px; align-items: center; }
.badge { font-size: 12px; font-weight: 600; text-transform: uppercase; letter-spacing: 0.05em; }
.badge.news { color: var(--news); } .badge.paper { color: var(--paper); } .badge.lecture { color: var(--lecture); }
.item { max-width: 760px; margin: 32px auto 0; }
.item h1 { font: 700 clamp(26px, 4.5vw, 40px)/1.2 var(--serif); margin: 10px 0 12px; }
.lead { font-size: 20px; color: var(--muted); margin: 0 0 12px; }
.source { font-size: 14px; color: var(--muted); border-bottom: 1px solid var(--line); padding-bottom: 18px; overflow-wrap: anywhere; }
.levels { display: flex; gap: 8px; flex-wrap: wrap; margin: 22px 0 8px; position: sticky; top: 0; background: var(--bg); padding: 10px 0; }
.panel { font-size: 18px; }
.panel h2, .panel h3 { font-family: var(--serif); }
.glossary h4 { font: 600 13px var(--sans); text-transform: uppercase; letter-spacing: 0.06em; color: var(--muted); margin: 18px 0 4px; }
.otitle { font-weight: 600; }
.note { font-size: 14px; color: var(--muted); border-left: 3px solid var(--accent); padding-left: 10px; }
.glossary { border-top: 1px solid var(--line); margin-top: 28px; }
.glossary dt { font-weight: 600; margin-top: 10px; }
.glossary dd { margin: 0; color: var(--muted); }
.empty { color: var(--muted); margin: 32px 0; }
.foot { color: var(--muted); font-size: 14px; border-top: 1px solid var(--line); margin-top: 56px; padding-top: 18px; padding-bottom: 32px; }
blockquote { border-left: 3px solid var(--line); margin-left: 0; padding-left: 14px; color: var(--muted); }
code { font-size: 0.9em; }