body {
  font-family: Arial, sans-serif;
  margin: 20px;
}

header {
  background-color: #333;
  color: #fff;
  padding: 20px;
  text-align: center;
}

nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

nav li {
  display: inline-block;
  margin-right: 20px;
}

nav a {
  color: #fff;
  text-decoration: none;
}

main {
  max-width: 800px;
  margin: 0 auto;
}

section {
  padding: 20px;
}

h1 {
  font-weight: bold;
}

button {
  background-color: #007bff;
  color: #fff;
  border: none;
  padding: 10px 20px;
  font-size: 16px;
}

button:hover {
  background-color: #0069d9;
}