body {
  font-family: Arial, sans-serif;
  margin: 20px;
  background: #f4f7fa;
  color: #333;
}
header {
  background: #0366d6;
  padding: 10px;
  color: white;
}
nav a {
  color: yellow;
  text-decoration: none;
  margin: 0 5px;
}
button {
  background: #0366d6;
  color: white;
  padding: 8px 15px;
  border: none;
  cursor: pointer;
  border-radius: 5px;
}
button:hover {
  background: #024a9f;
}