* { box-sizing: border-box; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  line-height: 1.6;
  max-width: 640px;
  margin: 0 auto;
  padding: 2rem 1rem;
  color: #222;
}
h1 { font-size: 1.75rem; margin-top: 0; }
h2 { font-size: 1.2rem; margin-top: 1.5rem; color: #333; }
a { color: #1967d2; text-decoration: none; }
a:hover { text-decoration: underline; }
nav { margin-bottom: 2rem; }
nav a { margin-right: 1rem; }
ul { padding-left: 1.25rem; }