body {
  font-family: Arial, sans-serif;
  margin: 0; padding: 20px;
  background: #f9f9f9;
}
header, footer {
  background: #333;
  color: white;
  padding: 10px;
  text-align: center;
}
nav a {
  color: white;
  margin: 0 10px;
  text-decoration: none;
}
section {
  margin: 20px 0;
}