:root { --fg: #222; --muted: #666; --accent: #2a6f97; --bg: #fff; --line: #e3e3e3; }
* { box-sizing: border-box; }
body { margin: 0; color: var(--fg); background: var(--bg); line-height: 1.7;
  font-family: system-ui, -apple-system, "PingFang SC", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif; }
a { color: var(--accent); }
main, header.site, footer.site { max-width: 60rem; margin: 0 auto; padding: 1rem; }
img { max-width: 100%; height: auto; }

header.site { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: .5rem; }
.brand { font-size: 1.4rem; font-weight: 600; text-decoration: none; color: var(--fg); }
.brand small { display: block; font-size: .8rem; font-weight: 400; color: var(--muted); }
nav ul { list-style: none; margin: 0; padding: 0; }
nav > ul { display: flex; flex-wrap: wrap; gap: .25rem 1rem; }
nav li { position: relative; }
nav a { text-decoration: none; }
nav summary { cursor: pointer; color: var(--accent); }
nav details ul { position: absolute; z-index: 1; min-width: 11rem; padding: .5rem .75rem;
  background: var(--bg); border: 1px solid var(--line); }

h1 { font-size: 1.6rem; line-height: 1.3; }
.meta, time, .speaker, .speakers span { color: var(--muted); }
.video { position: relative; aspect-ratio: 16 / 9; max-width: 100%; margin: 1rem 0; }
.video iframe { position: absolute; inset: 0; width: 100%; height: 100%; border: 0; }
.list { list-style: none; padding: 0; }
.list li { padding: .35rem 0; border-bottom: 1px solid var(--line); }
.list time { font-variant-numeric: tabular-nums; margin-right: .5rem; }
.speakers { columns: 14rem; }
.columns { display: grid; grid-template-columns: repeat(auto-fit, minmax(18rem, 1fr)); gap: 2rem; }
.pagination { display: flex; flex-wrap: wrap; gap: .5rem; list-style: none; padding: 0; }
.pagination .active a { font-weight: 700; color: var(--fg); }
footer.site { color: var(--muted); font-size: .9rem; border-top: 1px solid var(--line); margin-top: 2rem; }