body font-family: Arial, sans-serif; margin: 20px; background-color: #f4f4f4; .container max-width: 800px; margin: 0 auto; border: 1px solid #ccc; padding: 20px; border-radius: 8px; background-color: #fff; .header text-align: center; margin-bottom: 20px; .header h1 margin