body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
  background: #f3f3f3;
}
header {
  background-color: #004080;
  color: white;
  padding: 1rem;
  text-align: center;
}
nav a {
  margin: 0 1rem;
  color: white;
  text-decoration: none;
}
main {
  padding: 2rem;
  text-align: center;
}
button {
  padding: 0.8rem 1.2rem;
  background-color: #007bff;
  color: white;
  border: none;
  cursor: pointer;
}