: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;
            --danger-color: #dc3545;
            --chemistry-color: #8a2be2;
        } 
        .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);
        }
         
        /* Chemistry-specific styling */
        .chemical-formula {
            font-family: 'Cambria', 'Times New Roman', serif;
            font-style: italic;
            font-size: 1.1em;
        }
        
        .chemistry-highlight {
            color: var(--chemistry-color);
            font-weight: 600;
        }
        
        .reaction-container {
            background-color: #f8f9fa;
            border-radius: 8px;
            padding: 1.5rem;
            margin: 1.5rem 0;
            border: 1px solid #e9ecef;
            text-align: center;
            font-size: 1.25rem;
        }
        
        .reaction-arrow {
            margin: 0 1rem;
            font-weight: bold;
            color: var(--chemistry-color);
        }
        
        .summary-card {
            background: white;
            border-radius: 8px;
            padding: 1.5rem;
            border: 1px solid var(--border-color);
            margin-bottom: 1.5rem;
            box-shadow: 0 2px 4px rgba(0,0,0,0.05);
        }
        
        .summary-value {
            font-size: 1.5rem;
            font-weight: 700;
            color: var(--primary-color);
            margin-bottom: 0.5rem;
        }
        
        .summary-label {
            color: var(--text-muted);
            font-size: 0.9rem;
        }
        
        /* Chart Container */
        .chart-container {
            position: relative;
            height: 400px;
            width: 100%;
            margin: 2rem 0;
        }
        
        /* Financial Summary */
        .financial-summary {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
            gap: 1.5rem;
            margin: 2rem 0;
        }
        
        .financial-item {
            background: white;
            border-radius: 8px;
            padding: 1.5rem;
            border: 1px solid var(--border-color);
            box-shadow: 0 2px 4px rgba(0,0,0,0.05);
        }
        
        .financial-item h4 {
            font-size: 1rem;
            color: var(--text-muted);
            margin-bottom: 0.5rem;
        }
        
        .financial-item .value {
            font-size: 1.5rem;
            font-weight: 700;
            color: var(--primary-color);
        }
        
        .financial-item .detail {
            font-size: 0.9rem;
            color: var(--text-muted);
            margin-top: 0.5rem;
        }
         
        /* Responsive Adjustments */
        @media (max-width: 768px) { 
            .financial-summary {
                grid-template-columns: 1fr;
            }
        }
        
        /* Toggle switch for calculation modes */
        .calculation-modes {
            display: flex;
            background-color: var(--light-gray);
            border-radius: 6px;
            padding: 4px;
            margin-bottom: 1.5rem;
            flex-wrap: wrap;
        }
        
        .mode-btn {
            flex: 1;
            text-align: center;
            padding: 0.75rem;
            border-radius: 4px;
            cursor: pointer;
            transition: all 0.3s;
            font-weight: 600;
            min-width: 120px;
            margin: 2px;
        }
        
        .mode-btn.active {
            background-color: var(--primary-color);
            color: white;
        }
        
        /* Toast notifications */
        .toast-container {
            position: fixed;
            bottom: 20px;
            right: 20px;
            z-index: 1050;
        }
        
        /* Action buttons */
        .action-btn {
            background-color: white;
            border: 1px solid var(--border-color);
            border-radius: 6px;
            padding: 0.5rem 1rem;
            margin-left: 0.5rem;
            transition: all 0.3s;
            color: var(--text-color);
        }
        
        .action-btn:hover {
            background-color: var(--light-gray);
            color: var(--primary-color);
        }
        
        /* Chemical compound input styling */
        .compound-input {
            display: flex;
            margin-bottom: 1rem;
        }
        
        .compound-coefficient {
            width: 80px;
            margin-right: 10px;
        }
        
        .compound-formula {
            flex: 1;
            margin-right: 10px;
        }
        
        .compound-enthalpy {
            width: 150px;
        }
        
        .compound-actions {
            display: flex;
            align-items: center;
            margin-left: 10px;
        }
        
        .add-compound-btn {
            background-color: var(--success-color);
            color: white;
            border: none;
            border-radius: 50%;
            width: 36px;
            height: 36px;
            display: flex;
            align-items: center;
            justify-content: center;
            cursor: pointer;
            transition: all 0.3s;
        }
        
        .add-compound-btn:hover {
            background-color: #218838;
        }
        
        .remove-compound-btn {
            background-color: #dc3545;
            color: white;
            border: none;
            border-radius: 50%;
            width: 36px;
            height: 36px;
            display: flex;
            align-items: center;
            justify-content: center;
            cursor: pointer;
            transition: all 0.3s;
        }
        
        .remove-compound-btn:hover {
            background-color: #c82333;
        }
        
        /* Mode-specific form styling */
        .mode-form {
            display: none;
        }
        
        .mode-form.active {
            display: block;
        }
        
        /* Comparison table */
        .comparison-table {
            width: 100%;
            border-collapse: collapse;
            margin: 1.5rem 0;
        }
        
        .comparison-table th, .comparison-table td {
            padding: 0.75rem;
            text-align: left;
            border-bottom: 1px solid var(--border-color);
        }
        
        .comparison-table th {
            background-color: var(--light-gray);
            font-weight: 600;
        }
        
        .comparison-table tr:hover {
            background-color: rgba(44, 125, 160, 0.05);
        }
 
        /* Custom compound section */
        .custom-compound-section {
            background-color: #f8f9fa;
            border-radius: 8px;
            padding: 1.5rem;
            margin: 1.5rem 0;
            border: 1px solid #e9ecef;
        }
        
        .energy-diagram {
            position: relative;
            height: 300px;
            margin: 2rem 0;
            border-left: 2px solid #333;
            border-bottom: 2px solid #333;
        }
        
        .energy-level {
            position: absolute;
            left: 0;
            right: 0;
            height: 2px;
            background-color: #333;
        }
        
        .energy-label {
            position: absolute;
            left: -60px;
            transform: translateY(-50%);
            font-weight: bold;
        }
        
        .reaction-path {
            position: absolute;
            height: 2px;
            background-color: var(--primary-color);
            transition: all 0.5s ease;
        }
        
        .reaction-point {
            position: absolute;
            width: 12px;
            height: 12px;
            border-radius: 50%;
            transform: translate(-50%, -50%);
        }
        
        .invalid-feedback {
            display: none;
            width: 100%;
            margin-top: 0.25rem;
            font-size: 0.875em;
            color: var(--danger-color);
        }
        
        .form-control.is-invalid ~ .invalid-feedback {
            display: block;
        }