body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
  line-height: 1.6;
}
header {
  background: #0f172a;
  color: white;
  padding: 40px;
  text-align: center;
}
section {
  padding: 20px 40px;
}
footer {
  background: #f1f5f9;
  text-align: center;
  padding: 10px;
}
.btn {
  display: inline-block;
  margin-top: 15px;
  padding: 10px 20px;
  background: #2563eb;
  color: white;
  text-decoration: none;
  border-radius: 4px;
}