* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            background: linear-gradient(135deg, #74b9ff 0%, #0984e3 100%);
            min-height: 100vh;
            padding: 20px;
        }

        .container {
            max-width: 900px;
            margin: 0 auto;
            background: white;
            border-radius: 20px;
            box-shadow: 0 20px 40px rgba(0,0,0,0.1);
            overflow: hidden;
        }

        .header {
            background: linear-gradient(135deg, #74b9ff 0%, #0984e3 100%);
            color: white;
            padding: 30px;
            text-align: center;
        }

        .header h1 {
            font-size: 2.5em;
            margin-bottom: 10px;
        }

        .header p {
            font-size: 1.1em;
            opacity: 0.9;
        }

        .content {
            padding: 30px;
        }

        .mode-selector {
            display: flex;
            gap: 10px;
            margin-bottom: 30px;
            flex-wrap: wrap;
        }

        .mode-btn {
            padding: 12px 24px;
            border: none;
            border-radius: 25px;
            background: #f0f0f0;
            color: #333;
            cursor: pointer;
            transition: all 0.3s ease;
            font-weight: 500;
        }

        .mode-btn.active {
            background: linear-gradient(135deg, #74b9ff 0%, #0984e3 100%);
            color: white;
        }

        .mode-btn:hover {
            transform: translateY(-2px);
            box-shadow: 0 5px 15px rgba(0,0,0,0.2);
        }

        .calculator-section {
            display: none;
        }

        .calculator-section.active {
            display: block;
        }

        .info-box {
            background: #e3f2fd;
            padding: 20px;
            border-radius: 10px;
            margin-bottom: 30px;
            border-left: 4px solid #74b9ff;
        }

        .info-box h3 {
            color: #0984e3;
            margin-bottom: 15px;
        }

        .info-box p {
            color: #333;
            line-height: 1.6;
            margin-bottom: 10px;
        }

        .input-group {
            margin-bottom: 20px;
        }

        .input-group label {
            display: block;
            margin-bottom: 8px;
            font-weight: 600;
            color: #333;
        }

        .input-group input, .input-group select {
            width: 100%;
            padding: 12px;
            border: 2px solid #e0e0e0;
            border-radius: 10px;
            font-size: 16px;
            transition: border-color 0.3s ease;
        }

        .input-group input:focus, .input-group select:focus {
            outline: none;
            border-color: #74b9ff;
        }

        .unit-row {
            display: grid;
            grid-template-columns: 1fr auto 1fr;
            gap: 15px;
            align-items: end;
            margin-bottom: 20px;
        }

        .unit-row .input-group {
            margin-bottom: 0;
        }

        .unit-row .convert-btn {
            padding: 12px 20px;
            background: #74b9ff;
            color: white;
            border: none;
            border-radius: 10px;
            cursor: pointer;
            font-weight: 600;
            transition: all 0.3s ease;
        }

        .unit-row .convert-btn:hover {
            background: #0984e3;
            transform: translateY(-2px);
        }

        .calculate-btn {
            width: 100%;
            padding: 15px;
            background: linear-gradient(135deg, #74b9ff 0%, #0984e3 100%);
            color: white;
            border: none;
            border-radius: 10px;
            font-size: 18px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s ease;
            margin-bottom: 20px;
        }

        .calculate-btn:hover {
            transform: translateY(-2px);
            box-shadow: 0 10px 20px rgba(0,0,0,0.2);
        }

        .result {
            background: #f8f9fa;
            padding: 20px;
            border-radius: 10px;
            margin-top: 20px;
            display: none;
        }

        .result.show {
            display: block;
        }

        .result h3 {
            color: #0984e3;
            margin-bottom: 15px;
        }

        .result-item {
            display: flex;
            justify-content: space-between;
            margin-bottom: 10px;
            padding: 10px;
            background: white;
            border-radius: 8px;
        }

        .result-label {
            font-weight: 600;
            color: #333;
        }

        .result-value {
            font-weight: 700;
            color: #0984e3;
        }

        .comparison-chart {
            background: #e3f2fd;
            padding: 20px;
            border-radius: 10px;
            margin: 20px 0;
        }

        .comparison-chart h4 {
            color: #0984e3;
            margin-bottom: 15px;
            text-align: center;
        }

        .height-bar {
            background: #74b9ff;
            height: 30px;
            border-radius: 15px;
            margin: 10px 0;
            position: relative;
            overflow: hidden;
        }

        .height-bar-fill {
            background: linear-gradient(90deg, #74b9ff 0%, #0984e3 100%);
            height: 100%;
            border-radius: 15px;
            transition: width 0.5s ease;
        }

        .height-label {
            position: absolute;
            top: 50%;
            left: 10px;
            transform: translateY(-50%);
            color: white;
            font-weight: 600;
            font-size: 14px;
        }

        .percentile-info {
            background: #e8f5e8;
            padding: 20px;
            border-radius: 10px;
            margin-top: 20px;
            border-left: 4px solid #00b894;
        }

        .percentile-info h4 {
            color: #00b894;
            margin-bottom: 15px;
        }

        .growth-chart {
            background: #fff8e1;
            padding: 20px;
            border-radius: 10px;
            margin-top: 20px;
            border-left: 4px solid #fdcb6e;
        }

        .growth-chart h4 {
            color: #e17055;
            margin-bottom: 15px;
        }

        .tips {
            background: #e3f2fd;
            padding: 20px;
            border-radius: 10px;
            margin-top: 20px;
        }

        .tips h4 {
            color: #0984e3;
            margin-bottom: 10px;
        }

        .tips ul {
            list-style: none;
            padding-left: 0;
        }

        .tips li {
            margin-bottom: 8px;
            padding-left: 20px;
            position: relative;
        }

        .tips li:before {
            content: "📏";
            position: absolute;
            left: 0;
        }

        .back-link {
            display: inline-block;
            margin-top: 20px;
            color: #0984e3;
            text-decoration: none;
            font-weight: 600;
            transition: color 0.3s ease;
        }

        .back-link:hover {
            color: #74b9ff;
        }

        .unit-conversion-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
            gap: 15px;
            margin-top: 20px;
        }

        .conversion-card {
            background: white;
            padding: 15px;
            border-radius: 8px;
            border: 2px solid #e0e0e0;
            text-align: center;
        }

        .conversion-card h5 {
            color: #0984e3;
            margin-bottom: 10px;
        }

        .conversion-value {
            font-size: 1.2em;
            font-weight: bold;
            color: #333;
        }

        @media (max-width: 600px) {
            .header h1 {
                font-size: 2em;
            }
            
            .mode-selector {
                flex-direction: column;
            }
            
            .unit-row {
                grid-template-columns: 1fr;
                gap: 10px;
            }
            
            .result-item {
                flex-direction: column;
                gap: 5px;
            }
        }

        /* Cross-linking styles */
        .cross-links-section {
            max-width: 1000px;
            margin: 40px auto 20px;
            background-color: #ffffff;
            border-radius: 12px;
            box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
            padding: 30px;
        }
        
        .cross-links-section h2 {
            text-align: center;
            color: #2c3e50;
            margin-bottom: 30px;
            font-size: 1.8em;
            border-bottom: 3px solid #3498db;
            padding-bottom: 15px;
        }
        
        .cross-link-category {
            margin-bottom: 30px;
        }
        
        .cross-link-category h3 {
            color: #2c3e50;
            margin-bottom: 15px;
            font-size: 1.3em;
            padding-left: 10px;
            border-left: 4px solid #3498db;
        }
        
        .cross-link-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
            gap: 15px;
        }
        
        .cross-link-card {
            display: block;
            text-decoration: none;
            color: #34495e;
            background: #f8f9fa;
            border: 2px solid #e9ecef;
            border-radius: 8px;
            padding: 15px;
            transition: all 0.3s ease;
            position: relative;
            overflow: hidden;
        }
        
        .cross-link-card:hover {
            transform: translateY(-3px);
            box-shadow: 0 6px 20px rgba(52, 152, 219, 0.15);
            border-color: #3498db;
            background: #e3f2fd;
            color: #2c3e50;
        }
        
        .cross-link-card span {
            font-weight: 500;
            display: block;
            line-height: 1.4;
        }
        
        .cross-link-card::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            width: 4px;
            height: 100%;
            background: #3498db;
            transform: scaleY(0);
            transition: transform 0.3s ease;
        }
        
        .cross-link-card:hover::before {
            transform: scaleY(1);
        }
        
        @media (max-width: 768px) {
            .cross-links-section {
                margin: 20px;
                padding: 20px;
            }
            
            .cross-link-grid {
                grid-template-columns: 1fr;
                gap: 12px;
            }
            
            .cross-link-card {
                padding: 12px;
            }
        }