:root {
  color-scheme: light dark;
  --max-width: 720px;
  --fg: #1a1a1a;
  --bg: #ffffff;
  --accent: #2563eb;
}

@media (prefers-color-scheme: dark) {
  :root {
    --fg: #e5e5e5;
    --bg: #111111;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  color: var(--fg);
  background: var(--bg);
  line-height: 1.6;
}

header nav {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 1.5rem 1rem;
  display: flex;
  gap: 1.5rem;
}

header nav a {
  color: var(--accent);
  text-decoration: none;
  font-weight: 600;
}

main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1rem 3rem;
}

footer {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 1.5rem 1rem;
  font-size: 0.85rem;
  opacity: 0.7;
}

h1, h2, h3 { line-height: 1.2; }