body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  line-height: 1.6;
  margin: 0;
  padding: 20px;
  color: #333;
  max-width: 900px;
  margin: 0 auto;
}
nav {
  margin-bottom: 30px;
}
nav a {
  margin-right: 15px;
  text-decoration: none;
  color: #0066cc;
}
nav a:hover { text-decoration: underline; }
header h1 { margin-bottom: 5px; }
header p { color: #555; margin-top: 0; }
main { margin-top: 20px; }
h2 { color: #003366; margin-top: 30px; }
h3 { margin-top: 25px; margin-bottom: 8px; }
table { width: 100%; border-collapse: collapse; margin: 20px 0; }
th, td { border: 1px solid #999; padding: 10px; text-align: left; }
th { background-color: #f2f7ff; }
ul { margin-top: 8px; }