body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
  background: #f4f4f4;
}
header, nav, footer {
  background: #222;
  color: white;
  padding: 1em;
  text-align: center;
}
nav a {
  margin: 0 1em;
  color: #0ff;
  text-decoration: none;
}
main {
  padding: 2em;
  background: white;
}