:root {
  color-scheme: light dark;
  --fg: #111;
  --muted: #444;
  --line: #ccc;
  --link: #0645ad;
}
@media (prefers-color-scheme: dark) {
  :root {
    --fg: #eee;
    --muted: #bbb;
    --line: #444;
    --link: #8ab4f8;
  }
}
* { box-sizing: border-box; }
html { font-size: 18px; }
body {
  margin: 0 auto;
  max-width: 40rem;
  padding: 1.25rem 1rem 3rem;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.55;
  color: var(--fg);
}
h1 { font-size: 1.6rem; margin: 0.2rem 0 0.4rem; }
h2 { font-size: 1.15rem; margin-top: 1.6rem; }
h3 { font-size: 1rem; margin-top: 1.1rem; }
p, li { color: var(--fg); }
.sub, .brand, footer, nav { color: var(--muted); font-size: 0.95rem; }
.brand { margin: 0; letter-spacing: 0.02em; }
nav { margin: 0.8rem 0 1.2rem; padding: 0.6rem 0; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
nav span { font-weight: 600; color: var(--fg); }
a { color: var(--link); }
ul { padding-left: 1.2rem; }
footer { margin-top: 2.5rem; border-top: 1px solid var(--line); padding-top: 1rem; }
section { margin: 1.4rem 0; }