<!DOCTYPE html>
<html lang="id">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Kalkulator Luas Persegi Panjang</title>
    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.4.0/css/all.min.css">
    <style>
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
        }

        body {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: #fff;
            min-height: 100vh;
            display: flex;
            justify-content: center;
            align-items: center;
            padding: 20px;
        }

        .container {
            max-width: 900px;
            width: 100%;
            background: rgba(255, 255, 255, 0.1);
            border-radius: 20px;
            padding: 40px;
            backdrop-filter: blur(10px);
            border: 1px solid rgba(255, 255, 255, 0.2);
            box-shadow: 0 15px 35px rgba(0, 0, 0, 0.3);
        }

        header {
            text-align: center;
            margin-bottom: 40px;
        }

        h1 {
            font-size: 3rem;
            margin-bottom: 15px;
            color: #ffdd00;
            text-shadow: 0 0 15px rgba(255, 221, 0, 0.5);
        }

        .subtitle {
            font-size: 1.3rem;
            color: #e0e0e0;
            margin-bottom: 10px;
        }

        .content {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 40px;
            align-items: center;
        }

        .calculator-section {
            background: rgba(255, 255, 255, 0.05);
            padding: 30px;
            border-radius: 15px;
            border: 1px solid rgba(255, 255, 255, 0.1);
        }

        .formula-box {
            background: rgba(0, 0, 0, 0.3);
            padding: 20px;
            border-radius: 10px;
            text-align: center;
            margin-bottom: 25px;
            border: 1px solid rgba(255, 255, 255, 0.1);
        }

        .formula {
            font-size: 2rem;
            font-weight: bold;
            color: #4ecdc4;
        }

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

        .input-group label {
            display: block;
            margin-bottom: 10px;
            color: #e0e0e0;
            font-size: 1.1rem;
            font-weight: 500;
        }

        .input-group input {
            width: 100%;
            padding: 15px;
            border-radius: 10px;
            border: 2px solid rgba(255, 255, 255, 0.2);
            background: rgba(0, 0, 0, 0.3);
            color: white;
            font-size: 1.2rem;
            transition: all 0.3s ease;
        }

        .input-group input:focus {
            outline: none;
            border-color: #4ecdc4;
            box-shadow: 0 0 0 3px rgba(78, 205, 196, 0.3);
            transform: scale(1.02);
        }

        .calculate-btn {
            width: 100%;
            padding: 16px;
            background: linear-gradient(135deg, #4ecdc4, #45b7d1);
            border: none;
            border-radius: 10px;
            color: white;
            font-size: 1.3rem;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s ease;
            margin-top: 10px;
        }

        .calculate-btn:hover {
            transform: translateY(-3px);
            box-shadow: 0 8px 20px rgba(78, 205, 196, 0.4);
            background: linear-gradient(135deg, #45b7d1, #4ecdc4);
        }

        .calculate-btn:active {
            transform: translateY(1px);
        }

        .result {
            margin-top: 25px;
            padding: 20px;
            background: rgba(78, 205, 196, 0.15);
            border-radius: 10px;
            border-left: 5px solid #4ecdc4;
            font-size: 1.4rem;
            text-align: center;
            display: none;
            animation: fadeIn 0.5s ease;
        }

        .visualization {
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
        }

        .rectangle-container {
            position: relative;
            width: 250px;
            height: 160px;
            margin: 20px 0;
        }

        .rectangle {
            width: 100%;
            height: 100%;
            background: linear-gradient(135deg, #4ecdc4, #45b7d1);
            border: 4px solid white;
            box-shadow: 0 10px 25px rgba(0, 0, 0, 0.3);
            transition: all 0.5s ease;
            position: relative;
        }

        .dimension-label {
            position: absolute;
            background: rgba(0, 0, 0, 0.7);
            color: white;
            padding: 5px 10px;
            border-radius: 5px;
            font-size: 0.9rem;
            font-weight: bold;
        }

        .length-label {
            top: -35px;
            left: 50%;
            transform: translateX(-50%);
        }

        .width-label {
            right: -45px;
            top: 50%;
            transform: translateY(-50%) rotate(-90deg);
        }

        .area-grid {
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            display: none;
            pointer-events: none;
        }

        .grid-line {
            position: absolute;
            background: rgba(255, 255, 255, 0.3);
        }

        .horizontal-line {
            width: 100%;
            height: 1px;
            left: 0;
        }

        .vertical-line {
            width: 1px;
            height: 100%;
            top: 0;
        }

        .explanation {
            margin-top: 30px;
            padding: 25px;
            background: rgba(255, 255, 255, 0.05);
            border-radius: 15px;
            border: 1px solid rgba(255, 255, 255, 0.1);
        }

        .explanation h3 {
            color: #ffdd00;
            margin-bottom: 15px;
            font-size: 1.5rem;
        }

        .explanation p {
            line-height: 1.6;
            color: #e0e0e0;
            margin-bottom: 10px;
        }

        .examples {
            display: grid;
            grid-template-columns: repeat(3, 1fr);
            gap: 15px;
            margin-top: 20px;
        }

        .example-card {
            background: rgba(255, 255, 255, 0.05);
            padding: 15px;
            border-radius: 10px;
            text-align: center;
            border: 1px solid rgba(255, 255, 255, 0.1);
            transition: transform 0.3s ease;
            cursor: pointer;
        }

        .example-card:hover {
            transform: translateY(-5px);
            background: rgba(255, 255, 255, 0.1);
        }

        .properties {
            display: grid;
            grid-template-columns: repeat(2, 1fr);
            gap: 15px;
            margin-top: 20px;
        }

        .property-card {
            background: rgba(255, 255, 255, 0.05);
            padding: 15px;
            border-radius: 10px;
            text-align: center;
            border: 1px solid rgba(255, 255, 255, 0.1);
        }

        @keyframes fadeIn {
            from { opacity: 0; transform: translateY(10px); }
            to { opacity: 1; transform: translateY(0); }
        }

        @keyframes pulse {
            0% { transform: scale(1); }
            50% { transform: scale(1.05); }
            100% { transform: scale(1); }
        }

        @keyframes showGrid {
            from { opacity: 0; }
            to { opacity: 1; }
        }

        @media (max-width: 768px) {
            .content {
                grid-template-columns: 1fr;
            }
            
            h1 {
                font-size: 2.2rem;
            }
            
            .examples, .properties {
                grid-template-columns: 1fr;
            }
            
            .rectangle-container {
                width: 200px;
                height: 130px;
            }
        }
    </style>
</head>
<body>
    <div class="container">
        <header>
            <h1><i class="fas fa-rectangle-landscape"></i> Kalkulator Luas Persegi Panjang</h1>
            <p class="subtitle">Hitung luas persegi panjang dengan mudah dan cepat</p>
        </header>

        <div class="content">
            <div class="calculator-section">
                <div class="formula-box">
                    <div class="formula">L = p × l</div>
                    <p style="margin-top: 10px; color: #ccc;">Luas = Panjang × Lebar</p>
                </div>
                
                <div class="input-group">
                    <label for="rectangle-length"><i class="fas fa-ruler-vertical"></i> Panjang (p):</label>
                    <input type="number" id="rectangle-length" placeholder="Masukkan panjang" step="any" min="0">
                </div>
                
                <div class="input-group">
                    <label for="rectangle-width"><i class="fas fa-ruler-horizontal"></i> Lebar (l):</label>
                    <input type="number" id="rectangle-width" placeholder="Masukkan lebar" step="any" min="0">
                </div>
                
                <button class="calculate-btn" onclick="calculateRectangleArea()">
                    <i class="fas fa-calculator"></i> Hitung Luas
                </button>
                
                <div class="result" id="rectangle-result">
                    <i class="fas fa-check-circle"></i> <span id="result-text"></span>
                </div>
            </div>

            <div class="visualization">
                <h3 style="margin-bottom: 20px; color: #ffdd00;">Visualisasi Persegi Panjang</h3>
                <div class="rectangle-container">
                    <div class="rectangle" id="animated-rectangle">
                        <div class="area-grid" id="area-grid"></div>
                    </div>
                    <div class="dimension-label length-label" id="length-label">p</div>
                    <div class="dimension-label width-label" id="width-label">l</div>
                </div>
                <p style="text-align: center; color: #e0e0e0; margin-top: 20px;">
                    Persegi panjang memiliki dua pasang sisi yang sama panjang
                </p>
                <button onclick="toggleGrid()" style="margin-top: 15px; padding: 10px 20px; background: rgba(255,255,255,0.1); border: 1px solid rgba(255,255,255,0.3); color: white; border-radius: 8px; cursor: pointer;">
                    <i class="fas fa-th"></i> Tampilkan Grid Satuan
                </button>
            </div>
        </div>

        <div class="explanation">
            <h3><i class="fas fa-lightbulb"></i> Penjelasan Luas Persegi Panjang</h3>
            <p>Persegi panjang adalah bangun datar dua dimensi yang memiliki dua pasang sisi sejajar dengan panjang yang sama dan empat sudut siku-siku (90°).</p>
            <p><strong>Rumus Luas Persegi Panjang:</strong> L = p × l</p>
            <p>Dimana:
                <br>• L = Luas persegi panjang
                <br>• p = Panjang persegi panjang
                <br>• l = Lebar persegi panjang
            </p>
            
            <div class="properties">
                <div class="property-card">
                    <h4><i class="fas fa-arrows-alt-h"></i> Sisi</h4>
                    <p>Memiliki 4 sisi dengan 2 pasang sisi sejajar yang sama panjang</p>
                </div>
                <div class="property-card">
                    <h4><i class="fas fa-degree"></i> Sudut</h4>
                    <p>Keempat sudutnya siku-siku (90°)</p>
                </div>
                <div class="property-card">
                    <h4><i class="fas fa-ruler-combined"></i> Diagonal</h4>
                    <p>Memiliki 2 diagonal yang sama panjang</p>
                </div>
                <div class="property-card">
                    <h4><i class="fas fa-symmetry"></i> Simetri</h4>
                    <p>Memiliki 2 sumbu simetri</p>
                </div>
            </div>
            
            <div class="examples">
                <div class="example-card" onclick="setExample(8, 5)">
                    <strong>Contoh 1</strong>
                    <p>p = 8 cm, l = 5 cm</p>
                    <p>L = 8 × 5 = 40 cm²</p>
                </div>
                <div class="example-card" onclick="setExample(12, 7)">
                    <strong>Contoh 2</strong>
                    <p>p = 12 m, l = 7 m</p>
                    <p>L = 12 × 7 = 84 m²</p>
                </div>
                <div class="example-card" onclick="setExample(15, 10)">
                    <strong>Contoh 3</strong>
                    <p>p = 15 cm, l = 10 cm</p>
                    <p>L = 15 × 10 = 150 cm²</p>
                </div>
            </div>
        </div>
    </div>

    <script>
        let gridVisible = false;

        // Fungsi untuk menghitung luas persegi panjang
        function calculateRectangleArea() {
            const length = parseFloat(document.getElementById('rectangle-length').value);
            const width = parseFloat(document.getElementById('rectangle-width').value);
            const resultElement = document.getElementById('rectangle-result');
            const resultText = document.getElementById('result-text');
            const rectangle = document.getElementById('animated-rectangle');
            
            if (isNaN(length) || isNaN(width) || length <= 0 || width <= 0) {
                resultText.innerHTML = "Masukkan panjang dan lebar yang valid!";
                resultElement.style.display = 'block';
                resultElement.style.background = 'rgba(255, 100, 100, 0.15)';
                resultElement.style.borderLeftColor = '#ff6b6b';
                return;
            }
            
            const area = length * width;
            
            // Update hasil
            resultText.innerHTML = `Luas Persegi Panjang = <strong>${area.toFixed(2)}</strong> satuan²`;
            resultElement.style.display = 'block';
            resultElement.style.background = 'rgba(78, 205, 196, 0.15)';
            resultElement.style.borderLeftColor = '#4ecdc4';
            
            // Update visualisasi
            updateVisualization(length, width);
            
            // Animasi
            rectangle.style.animation = 'pulse 0.5s ease';
            setTimeout(() => {
                rectangle.style.animation = '';
            }, 500);
        }
        
        // Fungsi untuk memperbarui visualisasi
        function updateVisualization(length, width) {
            document.getElementById('length-label').textContent = length;
            document.getElementById('width-label').textContent = width;
            
            const rectangle = document.getElementById('animated-rectangle');
            rectangle.style.transform = 'scale(1)';
            
            // Update grid jika aktif
            if (gridVisible) {
                createGrid(length, width);
            }
        }
        
        // Fungsi untuk membuat grid satuan
        function createGrid(length, width) {
            const grid = document.getElementById('area-grid');
            grid.innerHTML = '';
            grid.style.display = 'block';
            
            const cellSize = 20; // Ukuran sel grid dalam pixel
            const cols = Math.min(Math.floor(length), 20); // Batasi maksimal 20 kolom
            const rows = Math.min(Math.floor(width), 15); // Batasi maksimal 15 baris
            
            // Garis horizontal
            for (let i = 0; i <= rows; i++) {
                const line = document.createElement('div');
                line.className = 'grid-line horizontal-line';
                line.style.top = `${(i / rows) * 100}%`;
                grid.appendChild(line);
            }
            
            // Garis vertikal
            for (let i = 0; i <= cols; i++) {
                const line = document.createElement('div');
                line.className = 'grid-line vertical-line';
                line.style.left = `${(i / cols) * 100}%`;
                grid.appendChild(line);
            }
            
            grid.style.animation = 'showGrid 0.5s ease';
        }
        
        // Fungsi untuk toggle grid
        function toggleGrid() {
            gridVisible = !gridVisible;
            const grid = document.getElementById('area-grid');
            
            if (gridVisible) {
                const length = parseFloat(document.getElementById('rectangle-length').value) || 1;
                const width = parseFloat(document.getElementById('rectangle-width').value) || 1;
                createGrid(length, width);
            } else {
                grid.style.display = 'none';
            }
        }
        
        // Fungsi untuk mengisi contoh
        function setExample(lengthValue, widthValue) {
            document.getElementById('rectangle-length').value = lengthValue;
            document.getElementById('rectangle-width').value = widthValue;
            calculateRectangleArea();
        }
        
        // Event listener untuk input agar bisa menggunakan Enter
        document.getElementById('rectangle-length').addEventListener('keypress', function(e) {
            if (e.key === 'Enter') {
                calculateRectangleArea();
            }
        });
        
        document.getElementById('rectangle-width').addEventListener('keypress', function(e) {
            if (e.key === 'Enter') {
                calculateRectangleArea();
            }
        });
        
        // Animasi saat halaman dimuat
        document.addEventListener('DOMContentLoaded', function() {
            const rectangle = document.getElementById('animated-rectangle');
            rectangle.style.transform = 'scale(0)';
            rectangle.style.transition = 'transform 0.8s ease';
            
            setTimeout(() => {
                rectangle.style.transform = 'scale(1)';
            }, 300);
            
            // Set contoh default
            setExample(10, 6);
        });
    </script>
</body>
</html>
