:root {
  color-scheme: light dark;
  --fg: #1d1d1f;
  --bg: #ffffff;
  --muted: #6e6e73;
  --link: #0066cc;
}
@media (prefers-color-scheme: dark) {
  :root { --fg: #f5f5f7; --bg: #1c1c1e; --muted: #a1a1a6; --link: #4da3ff; }
}
body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Noto Sans JP", sans-serif;
  line-height: 1.75;
}
main { max-width: 720px; margin: 0 auto; padding: 32px 16px 64px; }
h1 { font-size: 1.6rem; line-height: 1.4; }
h2 { font-size: 1.15rem; margin-top: 2em; }
a { color: var(--link); }
p.muted { color: var(--muted); }