body {
  max-width: 70ch;
  margin: 0 auto;
  background-color: #000; 
  color: #fff; 
}

a { color: #6cf; }

nav {
  text-align: center;
}

nav a {
  margin-right: 1em;
}

footer {
  padding-top: 4em;
  text-align: center;
}