body {
  background-color: #f0f0f0;
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
}
nav {
  background-color: #333;
  text-align: center;
  padding: 1em;
}
nav a {
  color: #fff;
  margin: 0 1em;
  text-decoration: none;
}
nav a:hover {
  color: #ff0000;
}
main {
  padding: 2em;
  background-color: #fff;
}
h2 {
  color: #006600;
}
.round {
  border-radius: 8px;
}
footer {
  background-color: #333;
  color: #fff;
  text-align: center;
  padding: 1em;
}