: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;
            --medical-red: #dc3545;
            --medical-green: #198754;
            --medical-yellow: #ffc107;
            --medical-orange: #fd7e14;
        }
          
        .hr-zone {
            padding: 1rem;
            border-radius: 8px;
            margin-bottom: 0.75rem;
            border-left: 5px solid;
            display: flex;
            justify-content: space-between;
            align-items: center;
        }
        
        .zone-details {
            flex-grow: 1;
        }
        
        .zone-range {
            font-weight: 700;
            font-size: 1.2rem;
        }
        
        .zone-percentage {
            background-color: rgba(255,255,255,0.8);
            padding: 0.25rem 0.5rem;
            border-radius: 4px;
            font-weight: 600;
        }
        
        .zone-very-light {
            background-color: rgba(169, 214, 229, 0.3);
            border-left-color: #a9d6e5;
        }
        
        .zone-light {
            background-color: rgba(40, 167, 69, 0.2);
            border-left-color: #28a745;
        }
        
        .zone-moderate {
            background-color: rgba(255, 193, 7, 0.2);
            border-left-color: #ffc107;
        }
        
        .zone-hard {
            background-color: rgba(253, 126, 20, 0.2);
            border-left-color: #fd7e14;
        }
        
        .zone-maximum {
            background-color: rgba(220, 53, 69, 0.2);
            border-left-color: #dc3545;
        }
         
        .fitness-info-box {
            background-color: rgba(40, 167, 69, 0.05);
            border-left: 3px solid var(--medical-green);
            padding: 1rem;
            border-radius: 0 4px 4px 0;
            margin: 1.5rem 0;
        }
         
        .calculation-methods {
            display: flex;
            background-color: var(--light-gray);
            border-radius: 6px;
            padding: 4px;
            margin-bottom: 1.5rem;
            flex-wrap: wrap;
        }
        
        .method-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;
        }
        
        .method-btn.active {
            background-color: var(--primary-color);
            color: white;
        }
        
        .toast-container {
            position: fixed;
            bottom: 20px;
            right: 20px;
            z-index: 1050;
        }
        
        .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);
        }
        
        .form-range {
            width: 100%;
            height: 1rem;
            padding: 0;
            background-color: transparent;
            -webkit-appearance: none;
        }
        
        .form-range:focus {
            outline: none;
        }
        
        .form-range::-webkit-slider-thumb {
            width: 1rem;
            height: 1rem;
            margin-top: -0.5rem;
            background-color: var(--primary-color);
            border: 0;
            border-radius: 1rem;
            -webkit-appearance: none;
        }
        
        .form-range::-webkit-slider-runnable-track {
            width: 100%;
            height: 0.5rem;
            cursor: pointer;
            animate: 0.2s;
            background: var(--light-gray);
            border-radius: 0.5rem;
        }
        
        .slider-value {
            background-color: var(--primary-color);
            color: white;
            padding: 0.25rem 0.5rem;
            border-radius: 4px;
            font-size: 0.8rem;
            margin-left: 0.5rem;
        }
        
        .zones-table {
            width: 100%;
            border-collapse: collapse;
            margin: 1.5rem 0;
        }
        
        .zones-table th, .zones-table td {
            padding: 0.75rem;
            text-align: left;
            border-bottom: 1px solid var(--border-color);
        }
        
        .zones-table th {
            background-color: var(--light-gray);
            font-weight: 600;
        }
        
        .zones-table tr:hover {
            background-color: rgba(44, 125, 160, 0.05);
        }
        
        .fitness-alert {
            background-color: rgba(255, 193, 7, 0.1);
            border-left: 4px solid var(--medical-yellow);
            padding: 1rem;
            margin: 1rem 0;
            border-radius: 0 4px 4px 0;
        }
        
        .fitness-caution {
            background-color: rgba(220, 53, 69, 0.1);
            border-left: 4px solid var(--medical-red);
            padding: 1rem;
            margin: 1rem 0;
            border-radius: 0 4px 4px 0;
        }
        
        .generating-indicator {
            display: none;
            text-align: center;
            padding: 1rem;
            color: var(--text-muted);
        }
        
        .intensity-indicator {
            display: inline-block;
            width: 12px;
            height: 12px;
            border-radius: 50%;
            margin-right: 8px;
        }
        
        .intensity-very-light {
            background-color: #a9d6e5;
        }
        
        .intensity-light {
            background-color: #28a745;
        }
        
        .intensity-moderate {
            background-color: #ffc107;
        }
        
        .intensity-hard {
            background-color: #fd7e14;
        }
        
        .intensity-maximum {
            background-color: #dc3545;
        }
        
        .ad-container {
            background-color: var(--light-gray);
            border-radius: 8px;
            padding: 1.5rem;
            margin-bottom: 1.5rem;
            text-align: center;
            border: 1px solid var(--border-color);
        }
        
        .ad-label {
            font-size: 0.75rem;
            color: var(--text-muted);
            text-transform: uppercase;
            letter-spacing: 1px;
            margin-bottom: 0.5rem;
        }
        
        .ad-placeholder {
            width: 100%;
            height: 250px;
            background-color: #f0f4f8;
            border: 1px dashed #dee2e6;
            border-radius: 6px;
            display: flex;
            align-items: center;
            justify-content: center;
            color: var(--text-muted);
            font-weight: 500;
        }
        
        .footer {
            background-color: var(--light-gray); 
            margin-top: 3rem;
            border-top: 1px solid var(--border-color);
        }
        
        @media (max-width: 768px) { 
            .hr-zone {
                flex-direction: column;
                align-items: flex-start;
            }
            
            .zone-range {
                margin-bottom: 0.5rem;
            }
        }
        
        .method-form {
            display: none;
        }
        
        .method-form.active {
            display: block;
        }