:root {
  color-scheme: light dark;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.6;
  color: #222;
  background: #fff;
}
body { max-width: 40rem; margin: 2rem auto; padding: 0 1rem; }
nav { display: flex; flex-wrap: wrap; gap: 1rem; }
a { color: #174ea6; }
@media (prefers-color-scheme: dark) {
  :root { color: #eee; background: #171717; }
  a { color: #9ec3ff; }
}