body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, sans-serif;
  max-width: 720px;
  margin: 4rem auto;
  padding: 0 1rem;
  line-height: 1.6;
  color: #222;
}

header {
  margin-bottom: 3rem;
}

nav a {
  margin-right: 1.2rem;
  text-decoration: none;
  color: #0055aa;
}

nav a:hover {
  text-decoration: underline;
}

h1, h2 {
  margin-top: 2.5rem;
}

footer {
  margin-top: 4rem;
  font-size: 0.9rem;
  color: #666;
}