body {
  font-family: Arial, sans-serif;
  margin: 0; padding: 0;
  background: #f9f9f9; color: #333;
}
header {
  background: #333; color: #fff;
  padding: 15px;
}
header h1 { margin: 0; }
nav a {
  color: #fff;
  margin-right: 15px;
  text-decoration: none;
}
main { padding: 20px; max-width: 800px; margin: auto; }
article { background: #fff; padding: 20px; border-radius: 10px; box-shadow: 0 0 10px rgba(0,0,0,0.1); }
footer {
  text-align: center; padding: 15px;
  background: #eee; margin-top: 20px;
}