body {
  font-family: Arial, sans-serif;
  max-width: 720px;
  margin: 40px auto;
  padding: 0 20px;
  background-color: #f5f5f5;
  color: #222;
}
header {
  text-align: center;
  margin-bottom: 40px;
}
section ul {
  padding-left: 20px;
}
footer {
  text-align: center;
  color: #888;
  font-size: 0.9em;
  margin-top: 50px;
}