:root {
  --bg: #ffffff; --fg: #1d1d1f; --muted: #6e6e73; --card: #f5f5f7; --accent: #0a84ff; --border: rgba(0,0,0,.08);
  color-scheme: light dark;
}
@media (prefers-color-scheme: dark) {
  :root { --bg: #000000; --fg: #f5f5f7; --muted: #a1a1a6; --card: #1c1c1e; --accent: #0a84ff; --border: rgba(255,255,255,.1); }
}
* { box-sizing: border-box; }
body { margin: 0; background: var(--bg); color: var(--fg);
  font: 17px/1.55 -apple-system, BlinkMacSystemFont, "SF Pro Text", "Helvetica Neue", Arial, sans-serif; }
main { max-width: 720px; margin: 0 auto; padding: 56px 20px 80px; }
header { display: flex; align-items: center; gap: 12px; margin-bottom: 40px; }
header a { color: inherit; text-decoration: none; font-weight: 600; font-size: 19px; }
nav { margin-left: auto; display: flex; gap: 20px; font-size: 15px; }
nav a { color: var(--muted); text-decoration: none; }
nav a:hover, nav a[aria-current] { color: var(--fg); }
h1 { font-size: 40px; line-height: 1.1; letter-spacing: -.02em; margin: 0 0 8px; }
h2 { font-size: 21px; margin: 36px 0 8px; }
.lead { font-size: 21px; color: var(--muted); margin: 0 0 32px; }
.meta { color: var(--muted); font-size: 14px; }
.card { background: var(--card); border: 1px solid var(--border); border-radius: 14px; padding: 20px 22px; margin: 24px 0; }
a { color: var(--accent); }
ul { padding-left: 22px; }
details { border-bottom: 1px solid var(--border); padding: 14px 0; }
summary { cursor: pointer; font-weight: 600; }
footer { margin-top: 64px; color: var(--muted); font-size: 14px; }