.mode-selector {
            display: flex;
            gap: 10px;
            margin-bottom: 30px;
            flex-wrap: wrap;
            justify-content: center;
        }
        .mode-btn {
            padding: 12px 24px;
            border: 2px solid var(--primary-color);
            border-radius: 5px;
            background: white;
            color: var(--primary-color);
            cursor: pointer;
            transition: all 0.3s ease;
            font-size: 16px;
        }
        .mode-btn.active {
            background: var(--primary-color);
            color: white;
        }
        .mode-btn:hover {
            background: var(--primary-color);
            color: white;
        }
        .calculator-section {
            display: none;
        }
        .calculator-section.active {
            display: block;
        }
        .calculator-section h2 {
            color: var(--primary-color);
            margin-top: 0;
            text-align: center;
        }
        .info-box {
            background-color: #f8f9fa;
            border: 1px solid #dee2e6;
            border-radius: 8px;
            padding: 20px;
            margin-bottom: 20px;
        }
        .info-box h4 {
            color: var(--primary-color);
            margin-top: 0;
        }
        .formula-display {
            background: #f5f5f5;
            border: 1px solid #ddd;
            border-radius: 5px;
            padding: 15px;
            margin-bottom: 20px;
            font-family: 'Courier New', monospace;
            font-size: 16px;
        }
        .compound-list {
            max-height: 300px;
            overflow-y: auto;
            border: 1px solid #ddd;
            border-radius: 5px;
            margin-bottom: 20px;
        }
        .compound-item {
            padding: 15px;
            border-bottom: 1px solid #eee;
            cursor: pointer;
            transition: background-color 0.3s ease;
        }
        .compound-item:hover {
            background-color: #f0f8ff;
        }
        .compound-item:last-child {
            border-bottom: none;
        }
        .compound-name {
            font-weight: bold;
            color: var(--primary-color);
            margin-bottom: 5px;
        }
        .compound-formula {
            color: #666;
            font-size: 14px;
        }