:root { --fg: #1d1d1f; --muted: #6e6e73; --link: #0a58ca; --bg: #fff; }
@media (prefers-color-scheme: dark) { :root { --fg: #f5f5f7; --muted: #a1a1a6; --link: #6ea8fe; --bg: #111; } }
body { margin: 0; background: var(--bg); color: var(--fg);
  font: 17px/1.55 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif; }
main { max-width: 640px; margin: 0 auto; padding: 40px 16px 64px; }
h1 { font-size: 2rem; line-height: 1.2; margin: 0.5em 0; }
h2 { font-size: 1.15rem; margin-top: 2em; }
a { color: var(--link); }
.muted, footer { color: var(--muted); font-size: 0.9rem; }
.lead { font-size: 1.25rem; }
footer { margin-top: 3em; }