body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
  background: #f2f2f2;
}
header, footer {
  background: #2d7f5e;
  color: white;
  padding: 1em;
  text-align: center;
}
nav {
  background: #3c9970;
  padding: 0.5em;
  text-align: center;
}
nav a {
  margin: 0 15px;
  color: white;
  text-decoration: none;
}
main {
  padding: 2em;
}