*{margin:0;padding:0;box-sizing:border-box}body{margin:0;padding:0;font-family:Arial,sans-serif;background-color:#f5f5f5}.home-container,.challenges-container,.settings-container,.add-challenge-container{max-width:1200px;margin:0 auto;padding:20px}.challenge-detail-container{max-width:1200px;margin:0 auto;padding:50px 20px}