* { box-sizing: border-box; margin: 0; padding: 0; }
body { 
  font-family: system-ui, -apple-system, sans-serif; 
  line-height: 1.6; 
  background: #f5f7fa;
  color: #333;
}
header { background: #4a86e8; padding: 1rem; }
nav a { 
  color: white; 
  text-decoration: none; 
  margin-right: 20px; 
  font-weight: 500;
}
nav a:hover { text-decoration: underline; }
main { padding: 2rem; max-width: 800px; margin: auto; }
h1 { color: #4a86e8; margin-bottom: 1rem; }