body { font-family: 'Arial', sans-serif; line-height: 1.6; color: #333; max-width: 1200px; margin: 0 auto; padding: 20px; }
        h1 { color: #FF6B35; text-align: center; }
        h2 { color: #4E9CAF; border-bottom: 2px solid #FF6B35; padding-bottom: 5px; }
        h3 { color: #555; }
        .nav { background: #FF6B35; padding: 10px; position: sticky; top: 0; z-index: 100; }
        .nav-mobile { display: none; }
        @media (max-width: 768px) {
            .nav-desktop { display: none; }
            .nav-mobile { display: block; }
        }
        .download-btn { background: #4CAF50; color: white; padding: 10px 20px; margin: 10px 0; display: inline-block; }
        .login-btn { background: #2196F3; color: white; padding: 10px 20px; margin: 10px 0; display: inline-block; }
        img { max-width: 100%; height: auto; margin: 20px 0; }
        .footer { margin-top: 40px; padding: 20px; background: #f5f5f5; }