:root {
  --bg: #ffffff;
  --fg: #1d1d1f;
  --muted: #6e6e73;
  --line: #e5e5ea;
  --accent: #0a66c2;
}
@media (prefers-color-scheme: dark) {
  :root { --bg: #111113; --fg: #f5f5f7; --muted: #a1a1a6; --line: #2c2c2e; --accent: #4da3ff; }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font: 16px/1.7 -apple-system, BlinkMacSystemFont, "PingFang SC", "Helvetica Neue", "Microsoft YaHei", sans-serif;
}
.wrap { max-width: 760px; margin: 0 auto; padding: 0 16px; }
header { border-bottom: 1px solid var(--line); }
header .wrap { display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 8px; padding-top: 16px; padding-bottom: 16px; }
.brand { font-weight: 600; color: var(--fg); text-decoration: none; }
nav a { color: var(--muted); text-decoration: none; margin-left: 16px; }
nav a:first-child { margin-left: 0; }
nav a:hover, a { color: var(--accent); }
main { padding: 48px 0; }
h1 { font-size: 28px; line-height: 1.3; margin: 0 0 8px; }
h2 { font-size: 20px; margin: 32px 0 8px; }
.sub { color: var(--muted); margin: 0 0 24px; }
dl { display: grid; grid-template-columns: max-content 1fr; gap: 6px 20px; margin: 0; }
dt { color: var(--muted); }
dd { margin: 0; }
footer { border-top: 1px solid var(--line); color: var(--muted); font-size: 14px; padding: 24px 0; }
@media (max-width: 520px) { dl { grid-template-columns: 1fr; } dt { margin-top: 8px; } }