:root {
            --primary-color: #2c7da0;
            --secondary-color: #a9d6e5;
            --accent-color: #01497c;
            --light-gray: #f8f9fa;
            --border-color: #eaeaea;
            --text-color: #333;
            --text-muted: #6c757d;
            --success-color: #28a745;
            --warning-color: #ffc107;
        }
         .container{max-width:1400px}
        .page-header {
            background: linear-gradient(135deg, rgba(169, 214, 229, 0.4) 0%, rgba(44, 125, 160, 0.4) 100%);
            padding: 1.5rem 0;
            margin-bottom: 2rem;
            border-bottom: 1px solid rgba(44, 125, 160, 0.2);
            position: relative;
            overflow: hidden;  color: var(--text-color);
        }
 
        .breadcrumb {
            background-color: transparent;
            padding: 0.5rem 0;
            margin-bottom: 0.5rem;
        }
        
        .breadcrumb-item a {
            color: var(--text-muted);
            text-decoration: none;
        }
        
        .breadcrumb-item.active {
            color: var(--text-color);
        }
         
        /* Periodic Table Styles */
        .periodic-table {
            display: grid;
            grid-template-columns: repeat(18, 1fr);
            grid-gap: 4px;
            margin: 2rem 0;
        }
        
        .element {
         //   aspect-ratio: 1/1;
            display: flex;
            flex-direction: column;
            justify-content: center;
            align-items: center;
            border-radius: 4px;
            cursor: pointer;
            transition: all 0.3s;
            padding: 4px;
            font-size: 0.8rem;
            text-align: center;
            position: relative;
            border: 1px solid rgba(0,0,0,0.1);
        }
        
        .element:hover {
            transform: scale(1.05);
            z-index: 10;
            box-shadow: 0 4px 8px rgba(0,0,0,0.15);
        }
        
        .element .atomic-number {
            position: absolute;
            top: 2px;
            left: 4px;
            font-size: 0.6rem;
            opacity: 0.8;
        }
        
        .element .symbol {
            font-weight: bold;
            font-size: 1rem;
            line-height: 1;
        }
        
        .element .name {
            font-size: 0.5rem;
            margin-top: 2px;
            opacity: 0.8;
        }
        
        .element .atomic-mass {
            font-size: 0.5rem;
            opacity: 0.7;
        }
        
        /* Element Category Colors */
        .alkali-metal { background-color: #ff9999; }
        .alkaline-earth-metal { background-color: #ffcc99; }
        .transition-metal { background-color: #ffeb99; }
        .post-transition-metal { background-color: #ccff99; }
        .metalloid { background-color: #99ffcc; }
        .nonmetal { background-color: #99ccff; }
        .halogen { background-color: #cc99ff; }
        .noble-gas { background-color: #ff99cc; }
        .lanthanide { background-color: #ccffcc; }
        .actinide { background-color: #ccccff; }
        
        /* Lanthanide and Actinide Series */
        .series-container {
            margin-top: 1.5rem;
            text-align: center;
        }
        
        .series-title {
            font-size: 0.9rem;
            font-weight: 600;
            margin-bottom: 0.5rem;
            color: var(--text-muted);
        }
        
        .series-table {
            display: grid;
            grid-template-columns: repeat(15, 1fr);
            grid-gap: 4px;
            margin: 0 auto;
            max-width: 900px;
        }
        
        /* Controls and Filters */
        .controls {
            display: flex;
            flex-wrap: wrap;
            gap: 1rem;
            margin-bottom: 1.5rem;
            align-items: center;
        }
        
        .search-box {
            flex-grow: 1;
            min-width: 200px;
        }
        
        .category-filter {
            display: flex;
            flex-wrap: wrap;
            gap: 0.5rem;
        }
        
        .category-btn {
            padding: 0.5rem 1rem;
            border: 1px solid var(--border-color);
            border-radius: 4px;
            background: white;
            cursor: pointer;
            transition: all 0.3s;
            font-size: 0.9rem;
        }
        
        .category-btn.active {
            background-color: var(--primary-color);
            color: white;
            border-color: var(--primary-color);
        }
        
        /* Element Details Panel */
        .element-details {
            display: none;
            background: white;
            border-radius: 8px;
            border: 1px solid var(--border-color);
            padding: 1.5rem;
            margin-top: 1.5rem;
            box-shadow: 0 2px 8px rgba(0,0,0,0.1);
        }
        
        .element-details.active {
            display: block;
        }
        
        .element-header {
            display: flex;
            align-items: center;
            margin-bottom: 1.5rem;
        }
        
        .element-color-box {
            width: 40px;
            height: 40px;
            border-radius: 4px;
            margin-right: 1rem;
            border: 1px solid rgba(0,0,0,0.1);
        }
        
        .element-info-grid {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
            gap: 1rem;
            margin-bottom: 1.5rem;
        }
        
        .info-item {
            display: flex;
            flex-direction: column;
        }
        
        .info-label {
            font-size: 0.8rem;
            color: var(--text-muted);
            margin-bottom: 0.25rem;
        }
        
        .info-value {
            font-weight: 600;
            font-size: 1rem;
        }
        
        /* Legend */
        .legend {
            display: flex;
            flex-wrap: wrap;
            gap: 0.5rem;
            margin: 1.5rem 0;
        }
        
        .legend-item {
            display: flex;
            align-items: center;
            font-size: 0.9rem;
        }
        
        .legend-color {
            width: 16px;
            height: 16px;
            border-radius: 2px;
            margin-right: 0.5rem;
            border: 1px solid rgba(0,0,0,0.1);
        }
        
        
        /* Responsive Adjustments */
        @media (max-width: 992px) {
            .periodic-table {
                grid-template-columns: repeat(9, 1fr);
                grid-gap: 2px;
            }
            
            .series-table {
                grid-template-columns: repeat(8, 1fr);
            }
        }
        
        @media (max-width: 768px) {
            .periodic-table {
                grid-template-columns: repeat(9, 1fr);
                grid-gap: 2px;
            }
            
            .series-table {
                grid-template-columns: repeat(6, 1fr);
            }
            
            .element {
                font-size: 0.7rem;
                padding: 2px;
            }
            
            .element .symbol {
                font-size: 0.8rem;
            }
 
            
            .element-info-grid {
                grid-template-columns: 1fr;
            }
        }
        
        @media (max-width: 576px) {
            .periodic-table {
                grid-template-columns: repeat(5, 1fr);
            }
            
            .series-table {
                grid-template-columns: repeat(4, 1fr);
            }
        }