body {
  font-family: system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
  line-height: 1.5;
  max-width: 42rem;
  margin: 0 auto;
  padding: 1.5rem;
  color: #1a1a1a;
  background: #fafafa;
}
header nav a { margin-right: 1rem; }
footer { margin-top: 2rem; font-size: 0.875rem; color: #555; }