body { font-family: 'Arial', sans-serif; line-height: 1.6; color: #333; max-width: 1200px; margin: 0 auto; padding: 20px; }
        h1 { color: #FF4500; text-align: center; }
        h2 { color: #008000; border-bottom: 2px solid #FFD700; }
        h3 { color: #4169E1; }
        .mobile-nav { display: none; }
        @media (max-width: 768px) {
            .desktop-nav { display: none; }
            .mobile-nav { display: block; }
        }
        .download-btn { background: #00FF00; padding: 10px 20px; margin: 15px 0; display: inline-block; }
        .login-btn { background: #1E90FF; padding: 10px 20px; margin: 15px 0; display: inline-block; }
        img { max-width: 100%; height: auto; margin: 20px 0; }