:root {
  color-scheme: light dark;
  --text: #1a1a1a;
  --muted: #555;
  --accent: #0066cc;
  --bg: #fafafa;
}

@media (prefers-color-scheme: dark) {
  :root {
    --text: #e8e8e8;
    --muted: #aaa;
    --accent: #7eb8ff;
    --bg: #121212;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, sans-serif;
  font-size: 18px;
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
}

main {
  max-width: 640px;
  margin: 0 auto;
  padding: 4rem 1.5rem;
}

header {
  margin-bottom: 2.5rem;
}

h1 {
  font-size: 2.25rem;
  margin: 0 0 0.25rem;
  letter-spacing: -0.02em;
}

.tagline {
  margin: 0;
  color: var(--muted);
  font-size: 1.1rem;
}

h2 {
  font-size: 1.25rem;
  margin: 0 0 0.5rem;
}

section + section {
  margin-top: 2rem;
}

ul {
  padding-left: 1.25rem;
  margin: 0;
}

li {
  margin-bottom: 0.5rem;
}

a {
  color: var(--accent);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}