body {
  font-family: Arial;
  margin: 0;
  text-align: center;
}

header {
  background: #0a2540;
  color: white;
  padding: 60px 20px;
}

.btn {
  display: inline-block;
  background: #25D366;
  color: white;
  padding: 15px 25px;
  margin-top: 20px;
  text-decoration: none;
  border-radius: 5px;
}

section {
  padding: 40px;
}

footer {
  background: #eee;
  padding: 20px;
}