/* 超级菜单样式 */
        .mega-menu {
            position: absolute;
            left: 0;
            width: 100%;
            background: white;
            box-shadow: 0 10px 30px rgba(0, 0, 0, 0.15);
            padding: 30px 30px 30px 80px;
            display: none;
            grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
            gap: 30px 10px;
            z-index: 99;
            
            opacity: 0;
            transform: translateY(10px);
            transition: opacity 0.3s, transform 0.3s;
        }
        
        .nav-item:hover .mega-menu {
            display: grid;
            opacity: 1;
            transform: translateY(0);
        }
        
        .mega-menu-column {
            min-width: 100px;
        }
        
        .mega-menu-header {
            font-weight: 700;
            font-size: 15px;
            margin-bottom: 5px;
            padding-bottom: 5px;
            
            color: #2c3e50;
        }
        
        .mega-menu-list {
            list-style: none;
        }
        
        .mega-menu-list li {
            margin-bottom: 0px;
        }
        
        .mega-menu-list a {
            text-decoration: none;
            color: #555;
            transition: color 0.2s;
            display: block;
            padding: 6px 0;
            font-size: .875em;
        }
        
        .mega-menu-list a:hover {
            color: #0d6efd !important;
            
        }
        
        /* 响应式设计 */
        @media (max-width: 992px) {
            .mega-menu {
                grid-template-columns: repeat(2, 1fr);
                padding: 20px;
            }
            
            .main-nav {
                flex-wrap: wrap;
            }
        }
        
        @media (max-width: 576px) {
            .mega-menu {
                grid-template-columns: 1fr;
            }
        }