body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  line-height: 1.6;
  background: #fdfdfd;
  color: #333;
}
header {
  background: #222;
  color: #fff;
  text-align: center;
  padding: 1rem 0.5rem;
}
header nav a {
  color: #ffd400;
  margin: 0 0.5rem;
  text-decoration: none;
}
header nav a:hover {
  text-decoration: underline;
}
main {
  max-width: 800px;
  margin: auto;
  padding: 1rem;
}
footer {
  text-align: center;
  padding: 1rem;
  color: #666;
}
pre {
  background: #f4f4f4;
  padding: 0.5rem;
  overflow-x: auto;
}