<style>
        .container {
            width: 100%;
            max-width: 1200px;
            display: flex;
            gap: 30px;
        }
        
        .sidebar {
            flex: 0 0 250px;
            background: white;
            border-radius: 10px;
            padding: 20px;
            box-shadow: 0 4px 10px rgba(0, 0, 0, 0.08);
            height: fit-content;
        }
        
        .categories {
            list-style: none;
        }
        
        .categories h2 {
            margin-bottom: 15px;
            padding-bottom: 10px;
            border-bottom: 2px solid #4a6491;
            color: #2c3e50;
        }
        
        .category-item {
            margin-bottom: 5px;
            border-radius: 6px;
            overflow: hidden;
        }
        
        .category-header {
            padding: 12px 15px;
            border-radius: 6px;
            transition: all 0.3s ease;
            cursor: pointer;
            display: flex;
            align-items: center;
            justify-content: space-between;
            background: #f8f9fa;
        }
        
        .category-header:hover {
            background: #007bff;
        }
        
        .category-header.active {
            background: #007bff;
            color: #fff;
        }
        
        .category-header i:last-child {
            transition: transform 0.3s ease;
            font-size: 0.9rem;
        }
        
        .category-header.active i:last-child {
            transform: rotate(90deg);
        }
        
        .subcategories {
            list-style: none;
            max-height: 0;
            overflow: hidden;
            transition: max-height 0.4s ease;
        }
        
        .category-item.active .subcategories {
            max-height: 700px;
        }
        
        .subcategories li {
            font-size:12px;
            padding: 10px;
            transition: all 0.3s ease;
            cursor: pointer;
            display: flex;
            align-items: center;
        }
        
        .subcategories li:hover {
            background: eef2f7;;
            transform: translateX(5px);
        }
        
        .subcategories li.active {
            background: #eef2f7;
            color: #007bff;
            font-weight: 500;
        }
        
        .subcategories li i {
            margin-right: 10px;
            font-size: 0.9rem;
        }
        
        .content {
            flex: 1;
            background: white;
            border-radius: 10px;
            padding: 20px;
            box-shadow: 0 4px 10px rgba(0, 0, 0, 0.08);
            display: flex;
            flex-direction: column;
            justify-content: center;
            align-items: center;
        }
        
        .content h2 {
            color: #2c3e50;
            margin-bottom: 20px;
        }
        
        .content p {
            color: #666;
            text-align: center;
            max-width: 600px;
            line-height: 1.8;
        }
        
        @media (max-width: 900px) {
            .container {
                flex-direction: column;
            }
            
            .sidebar {
                flex: 1;
                margin-bottom: 20px;
                width: 100%;
            }
        }
        .on1{
            color:#fff;
        }
        .on1:hover{
            cursor: pointer;
            color:#fff;
        }
    </style>