/* 侧边栏样式 */
        .sidebar {
            width: 260px;
            background: linear-gradient(135deg, #2c3e50, #1a2530);
            color: white;
            height: 100vh;
            overflow-y: auto;
            transition: all 0.3s ease;
            box-shadow: 3px 0 15px rgba(0, 0, 0, 0.1);
            position: sticky;
            top: 0;
        }
        
        .sidebar-header {
            padding: 24px 20px;
            border-bottom: 1px solid rgba(255, 255, 255, 0.1);
            display: flex;
            align-items: center;
        }
        
        .logo {
            font-size: 24px;
            font-weight: 700;
            color: #3498db;
            display: flex;
            align-items: center;
        }
        
        .logo i {
            margin-right: 10px;
            font-size: 28px;
        }
        
        .nav-menu {
            padding: 15px 0;
        }
        
        .nav-item {
            position: relative;
            margin-bottom: 40px;
        }
        
        .nav-link {
            display: flex;
            align-items: center;
            padding: 14px 20px;
            color: #bdc3c7;
            text-decoration: none;
            transition: all 0.3s ease;
            border-left: 3px solid transparent;
        }
        
        .nav-link:hover {
            background-color: rgba(255, 255, 255, 0.05);
            color: white;
            border-left-color: #3498db;
        }
        
        .nav-link.active {
            background-color: rgba(52, 152, 219, 0.1);
            color: white;
            border-left-color: #3498db;
        }
        
        .nav-icon {
            margin-right: 12px;
            font-size: 18px;
            width: 24px;
            text-align: center;
        }
        
        .nav-text {
            flex: 1;
        }
        
        .nav-arrow {
            transition: transform 0.3s ease;
        }
        
        .nav-item.active .nav-arrow {
            transform: rotate(90deg);
        }
        
        /* 一级下拉菜单 */
        .submenu {
            max-height: 0;
            overflow: hidden;
            transition: max-height 0.4s ease;
/*            background-color: rgba(0, 0, 0, 0.2);*/
        }
        
        .nav-item.active .submenu {
            max-height: 500px;
        }
        
        .submenu-item {
            position: relative;
        }
        
        .submenu-link {
            display: flex;
            align-items: center;
            padding: 12px 20px 12px 50px;
            color: #000000;
            text-decoration: none;
            transition: all 0.3s ease;
        }
        
        .submenu-link:hover {
            background-color: rgba(255, 255, 255, 0.05);
            color: #bf9999;
        }
        
        .submenu-link.active {
            color: #3498db;
            background-color: rgba(52, 152, 219, 0.1);
        }
        
        /* 二级下拉菜单 */
        .submenu-lvl2 {
            max-height: 0;
            overflow: hidden;
            transition: max-height 0.4s ease;
            background-color: rgba(0, 0, 0, 0.1);
        }
        
        .submenu-item.active .submenu-lvl2 {
            max-height: 300px;
        }
        
        .submenu-lvl2-link {
            display: flex;
            align-items: center;
            padding: 10px 20px 10px 70px;
            color: #7f8c8d;
            text-decoration: none;
            transition: all 0.3s ease;
            font-size: 14px;
        }
        
        .submenu-lvl2-link:hover {
            background-color: rgba(255, 255, 255, 0.05);
            color: white;
        }
        
        /* 主内容区域 */
        .main-content {
            flex: 1;
            padding: 30px;
            overflow-y: auto;
        }
        
        .content-header {
            margin-bottom: 30px;
        }
        
        .content-header h1 {
            font-size: 28px;
            color: #2c3e50;
            margin-bottom: 10px;
        }
        
        .content-header p {
            color: #7f8c8d;
            font-size: 16px;
        }
        
        .card {
            background: white;
            border-radius: 10px;
            padding: 25px;
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
            margin-bottom: 25px;
        }
        
        .card h2 {
            color: #2c3e50;
            margin-bottom: 15px;
            font-size: 20px;
        }
        
        .card p {
            color: #5d6d7e;
            line-height: 1.6;
        }
        
        /* 响应式设计 */
        @media (max-width: 768px) {
            .sidebar {
                width: 70px;
            }
            
            .logo span, .nav-text, .nav-arrow {
                display: none;
            }
            
            .nav-icon {
                margin-right: 0;
                font-size: 20px;
            }
            
            .nav-link {
                justify-content: center;
                padding: 18px 0;
            }
            
            .submenu-link, .submenu-lvl2-link {
                padding-left: 20px;
            }
            
            .sidebar:hover {
                width: 260px;
            }
            
            .sidebar:hover .logo span, 
            .sidebar:hover .nav-text, 
            .sidebar:hover .nav-arrow {
                display: inline-block;
            }
            
            .sidebar:hover .nav-icon {
                margin-right: 12px;
            }
            
            .sidebar:hover .nav-link {
                justify-content: flex-start;
                padding: 14px 20px;
            }
        }