body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  margin: 40px;
  max-width: 800px;
  line-height: 1.6;
}
h1 { margin-bottom: 0; }
header p { color: #666; }
ul { padding-left: 20px; }
footer { margin-top: 40px; font-size: 0.9em; color: #777; }
a { color: #007aff; text-decoration: none; }
a:hover { text-decoration: underline; }