body { font-family: Arial, sans-serif; margin: 0; padding: 20px; text-align: center; }
header { background: #4A90E2; color: white; padding: 40px 20px; }
.btn { background: #25D366; color: white; padding: 15px 30px; text-decoration: none; border-radius: 8px; display: inline-block; margin-top: 20px; }