body {
  font-family: Arial, sans-serif;
  color: #333;
  max-width: 800px;
  margin: 0 auto;
  padding: 1em;
}
header, footer {
  text-align: center;
  margin-bottom: 2em;
}
nav a {
  margin: 0 0.5em;
  text-decoration: none;
  color: #0066cc;
}
nav a:hover {
  text-decoration: underline;
}
aside {
  margin-top: 2em;
  padding: 1em;
  background: #f9f9f9;
}