: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;
            --frequency-blue: #2c7da0;
            --frequency-green: #198754;
            --frequency-yellow: #ffc107;
            --frequency-orange: #fd7e14;
            --frequency-red: #dc3545;
            --frequency-purple: #6f42c1;
        }
          
        
        /* Frequency Summary */
        .frequency-summary {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
            gap: 1.5rem;
            margin: 2rem 0;
        }
        
        .frequency-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);
        }
        
        .frequency-item h4 {
            font-size: 1rem;
            color: var(--text-muted);
            margin-bottom: 0.5rem;
        }
        
        .frequency-item .value {
            font-size: 1.5rem;
            font-weight: 700;
            color: var(--primary-color);
        }
        
        .frequency-item .detail {
            font-size: 0.9rem;
            color: var(--text-muted);
            margin-top: 0.5rem;
        }
         
        .frequency-info-box {
            background-color: rgba(220, 53, 69, 0.05);
            border-left: 3px solid var(--frequency-red);
            padding: 1rem;
            border-radius: 0 4px 4px 0;
            margin: 1.5rem 0;
        }
        
        @media (max-width: 768px) { 
            .frequency-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);
        }
        
        /* Range slider styling */
        .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;
        }
        
        /* Input group styling */
        .input-group {
            margin-bottom: 1rem;
        }
        
        /* 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);
        }
        
        /* Frequency-specific styling */
        .frequency-alert {
            background-color: rgba(220, 53, 69, 0.1);
            border-left: 4px solid var(--frequency-red);
            padding: 1rem;
            margin: 1rem 0;
            border-radius: 0 4px 4px 0;
        }
        
        .normal-frequency {
            color: var(--frequency-green);
            font-weight: 600;
        }
        
        .high-frequency {
            color: var(--frequency-red);
            font-weight: 600;
        }
        
        .reference-table {
            width: 100%;
            border-collapse: collapse;
            margin: 1.5rem 0;
        }
        
        .reference-table th, .reference-table td {
            padding: 0.75rem;
            text-align: left;
            border: 1px solid var(--border-color);
        }
        
        .reference-table th {
            background-color: var(--light-gray);
            font-weight: 600;
        }
        
        .reference-table tr:nth-child(even) {
            background-color: rgba(44, 125, 160, 0.05);
        }
        
        .generating-indicator {
            display: none;
            text-align: center;
            padding: 1rem;
            color: var(--text-muted);
        }
        
        /* Frequency range specific styles */
        .frequency-input-group {
            display: flex;
            align-items: center;
            margin-bottom: 1rem;
        }
        
        .frequency-input {
            width: 150px;
            margin-right: 1rem;
        }
        
        .frequency-range-indicator {
            padding: 1rem;
            border-radius: 8px;
            margin: 1rem 0;
            border-left: 5px solid;
        }
        
        .frequency-sub-audio {
            background-color: rgba(108, 117, 125, 0.1);
            border-left-color: #6c757d;
        }
        
        .frequency-audio {
            background-color: rgba(0, 123, 255, 0.1);
            border-left-color: #007bff;
        }
        
        .frequency-ultrasonic {
            background-color: rgba(40, 167, 69, 0.1);
            border-left-color: var(--frequency-green);
        }
        
        .frequency-rf {
            background-color: rgba(255, 193, 7, 0.1);
            border-left-color: var(--frequency-yellow);
        }
        
        .frequency-microwave {
            background-color: rgba(253, 126, 20, 0.1);
            border-left-color: var(--frequency-orange);
        }
        
        .frequency-infrared {
            background-color: rgba(220, 53, 69, 0.1);
            border-left-color: var(--frequency-red);
        }
        
        .frequency-visible-light {
            background-color: rgba(111, 66, 193, 0.1);
            border-left-color: var(--frequency-purple);
        }
        
        .frequency-uv {
            background-color: rgba(32, 201, 151, 0.1);
            border-left-color: #20c997;
        }
        
        .frequency-chart-container {
            position: relative;
            height: 300px;
            width: 100%;
            margin: 1.5rem 0;
        }
        
        .frequency-status-indicator {
            display: inline-block;
            width: 12px;
            height: 12px;
            border-radius: 50%;
            margin-right: 8px;
        }
        
        .status-sub-audio {
            background-color: #6c757d;
        }
        
        .status-audio {
            background-color: #007bff;
        }
        
        .status-ultrasonic {
            background-color: var(--frequency-green);
        }
        
        .status-rf {
            background-color: var(--frequency-yellow);
        }
        
        .status-microwave {
            background-color: var(--frequency-orange);
        }
        
        .status-infrared {
            background-color: var(--frequency-red);
        }
        
        .status-visible-light {
            background-color: var(--frequency-purple);
        }
        
        .status-uv {
            background-color: #20c997;
        }
        
        /* Medium selector */
        .medium-selector {
            display: flex;
            flex-wrap: wrap;
            gap: 0.5rem;
            margin-bottom: 1rem;
        }
        
        .medium-option {
            padding: 0.5rem 1rem;
            border: 1px solid var(--border-color);
            border-radius: 4px;
            cursor: pointer;
            transition: all 0.3s;
            font-weight: 500;
        }
        
        .medium-option:hover {
            background-color: rgba(44, 125, 160, 0.1);
        }
        
        .medium-option.active {
            background-color: var(--primary-color);
            color: white;
            border-color: var(--primary-color);
        }
        
        /* Unit selector */
        .unit-selector {
            display: flex;
            flex-wrap: wrap;
            gap: 0.5rem;
            margin-bottom: 1rem;
        }
        
        .unit-option {
            padding: 0.5rem 1rem;
            border: 1px solid var(--border-color);
            border-radius: 4px;
            cursor: pointer;
            transition: all 0.3s;
            font-weight: 500;
        }
        
        .unit-option:hover {
            background-color: rgba(44, 125, 160, 0.1);
        }
        
        .unit-option.active {
            background-color: var(--primary-color);
            color: white;
            border-color: var(--primary-color);
        }
        
        /* Conversion types */
        .conversion-types {
            display: flex;
            flex-wrap: wrap;
            gap: 0.5rem;
            margin-bottom: 1.5rem;
        }
        
        .conversion-type {
            padding: 0.75rem 1.5rem;
            border: 1px solid var(--border-color);
            border-radius: 6px;
            cursor: pointer;
            transition: all 0.3s;
            font-weight: 600;
            text-align: center;
            flex: 1;
            min-width: 150px;
        }
        
        .conversion-type:hover {
            background-color: rgba(44, 125, 160, 0.1);
        }
        
        .conversion-type.active {
            background-color: var(--primary-color);
            color: white;
            border-color: var(--primary-color);
        }
        
        /* Signal visualization */
        .signal-visualization {
            position: relative;
            height: 200px;
            width: 100%;
            margin: 1.5rem 0;
            background-color: #f8f9fa;
            border-radius: 8px;
            overflow: hidden;
            border: 1px solid var(--border-color);
        }
        
        .signal-canvas {
            width: 100%;
            height: 100%;
        }
        
        /* Note frequency keyboard */
        .keyboard-visualization {
            display: flex;
            flex-direction: column;
            margin: 1.5rem 0;
            border: 1px solid var(--border-color);
            border-radius: 8px;
            overflow: hidden;
        }
        
        .keyboard-row {
            display: flex;
            height: 40px;
        }
        
        .keyboard-key {
            flex: 1;
            display: flex;
            align-items: center;
            justify-content: center;
            border-right: 1px solid var(--border-color);
            border-bottom: 1px solid var(--border-color);
            font-weight: 600;
            transition: all 0.2s;
            cursor: pointer;
        }
        
        .keyboard-key.active {
            background-color: var(--primary-color);
            color: white;
        }
        
        .keyboard-key:hover {
            background-color: rgba(44, 125, 160, 0.1);
        }
        
        .keyboard-key:last-child {
            border-right: none;
        }
        
        .keyboard-row:last-child .keyboard-key {
            border-bottom: none;
        }