/* 响应式设计 */
    @media (max-width: 992px) {
        main {
            flex-direction: column;
        }
            
        .sidebar {
            flex: 1;
            position: static;
        }
            
        .page-title {
            font-size: 2.2rem;
        }
         .content, .sidebar {
            padding: 15px;
        }
    }
        
    @media (max-width: 768px) {    
            
        .header-content {
            flex-direction: column;
            align-items: flex-start;
        }
            
        nav {
            margin-top: 15px;
            width: 100%;
        }
            
        nav ul {
            justify-content: space-between;
            flex-wrap: wrap;
        }
            
        nav li {
            margin-left: 0;
            margin-right: 10px;
            margin-bottom: 10px;
        }
            
        .content, .sidebar {
            padding: 10px;
        }
    }