: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;
            --biology-green: #4caf50;
            --biology-blue: #2196f3;
            --biology-purple: #9c27b0;
            --cell-culture-orange: #ff9800;
        }
         
        .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);
        }
         
        
        /* Responsive Adjustments */
        @media (max-width: 768px) {
 
            .hemocytometer-grid {
                width: 250px;
                height: 250px;
            }
        }
        
        /* 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(--cell-culture-orange);
            color: white;
        }
        
        /* Mode forms - FIXED: Hide non-active forms */
        .mode-form {
            display: none;
        }
        
        .mode-form.active {
            display: block;
        }
         
        /* Analysis table */
        .analysis-table {
            width: 100%;
            border-collapse: collapse;
            margin: 1.5rem 0;
        }
        
        .analysis-table th, .analysis-table td {
            padding: 0.75rem;
            text-align: left;
            border-bottom: 1px solid var(--border-color);
        }
        
        .analysis-table th {
            background-color: var(--light-gray);
            font-weight: 600;
        }
        
        .analysis-table tr:hover {
            background-color: rgba(44, 125, 160, 0.05);
        }
        
        /* Special styling for cell culture themed elements */
        .cell-culture-highlight {
            background-color: rgba(255, 152, 0, 0.1);
            border-left: 3px solid var(--cell-culture-orange);
            padding: 1rem;
            border-radius: 0 4px 4px 0;
            margin: 1.5rem 0;
        }
        
        .generating-indicator {
            display: none;
            text-align: center;
            padding: 1rem;
            color: var(--primary-color);
            font-weight: 600;
        }
        
        /* Hemocytometer visualization */
        .hemocytometer-container {
            background-color: #f0f8ff;
            border-radius: 8px;
            padding: 2rem;
            margin: 2rem 0;
            position: relative;
            border: 1px solid var(--border-color);
            min-height: 400px;
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
        }
        
        .hemocytometer-grid {
            width: 300px;
            height: 300px;
            background-color: white;
            border: 2px solid #333;
            position: relative;
            margin: 0 auto;
        }
        
        .grid-square {
            position: absolute;
            border: 1px solid #ccc;
            background-color: rgba(255, 255, 255, 0.8);
        }
        
        .cell-dot {
            position: absolute;
            width: 6px;
            height: 6px;
            background-color: #ff5252;
            border-radius: 50%;
            transform: translate(-50%, -50%);
        }
        
        .counting-instructions {
            margin-top: 1rem;
            text-align: center;
            font-size: 0.9rem;
            color: var(--text-muted);
        }
        
        /* Input validation */
        .is-invalid {
            border-color: #dc3545;
            box-shadow: 0 0 0 0.2rem rgba(220, 53, 69, 0.25);
        }
        
        .invalid-feedback {
            display: none;
            width: 100%;
            margin-top: 0.25rem;
            font-size: 0.875em;
            color: #dc3545;
        }
        
        .is-invalid ~ .invalid-feedback {
            display: block;
        }