/* 响应式设计 */
@media (max-width: 992px) {
    .hero h2 {
        font-size: 2.3rem;
    }
    
    .hero p {
        font-size: 1.2rem;
    }
    
    nav ul {
        display: none;
    }
    
    .mobile-menu-btn {
        display: block;
    }
}

@media (max-width: 768px) {
    .hero {
        padding: 4rem 0;
    }
    
    .hero h2 {
        font-size: 2rem;
    }
    
    .hero p {
        font-size: 1.1rem;
    }
    
    .section {
        margin: 3rem 0;
    }
    
    .card-grid {
        grid-template-columns: 1fr;
    }
    
    header .container {
        flex-direction: column;
        text-align: center;
    }
    
    header .logo {
        margin-bottom: 15px;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 576px) {
    .container {
        width: 95%;
    }
    
    .hero h2 {
        font-size: 1.8rem;
    }
    
    .section-header h2 {
        font-size: 1.8rem;
    }
    
    .btn {
        display: block;
        width: 100%;
        margin-top: 15px;
    }
    
    footer .copyright {
        font-size: 0.85rem;
    }
}