:root {
            --primary: #2c3e50;
            --secondary: #3498db;
            --accent: #e74c3c;
            --light: #ecf0f1;
            --dark: #34495e;
            --success: #27ae60;
            --warning: #f39c12;
        }
        
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
        }
        
        body {
            background-color: #f8f9fa;
            color: #333;
            line-height: 1.6;
            padding: 20px;
            max-width: 90%px;
            margin: 0 auto;
        }
        
        header {
            text-align: center;
            padding: 30px 0;
            margin-bottom: 30px;
            background: linear-gradient(135deg, var(--primary), var(--secondary));
            color: white;
            border-radius: 10px;
            box-shadow: 0 5px 15px rgba(0,0,0,0.1);
        }
        
        h1 {
            font-size: 2.5rem;
            margin-bottom: 10px;
            font-weight: 700;
        }
        
        .subtitle {
            font-size: 1.2rem;
            opacity: 0.9;
            max-width: 800px;
            margin: 0 auto;
        }
        
        .content-container {
            display: grid;
            grid-template-columns: 1fr;
            gap: 30px;
        }
        
        .section {
            background: white;
            border-radius: 10px;
            padding: 25px;
            box-shadow: 0 3px 10px rgba(0,0,0,0.08);
            transition: transform 0.3s ease, box-shadow 0.3s ease;
        }
        
        .section:hover {
            transform: translateY(-5px);
            box-shadow: 0 10px 20px rgba(0,0,0,0.1);
        }
        
        h2 {
            color: var(--primary);
            border-bottom: 3px solid var(--secondary);
            padding-bottom: 10px;
            margin-bottom: 20px;
            font-size: 1.8rem;
        }
        
        h3 {
            color: var(--secondary);
            margin: 20px 0 15px;
            font-size: 1.4rem;
        }
        
        h4 {
            color: var(--dark);
            margin: 15px 0 10px;
            font-size: 1.2rem;
        }
        
        p {
            margin-bottom: 15px;
            text-align: justify;
        }
        
        ul, ol {
            padding-left: 25px;
            margin-bottom: 20px;
        }
        
        li {
            margin-bottom: 8px;
        }
        
        b {
            color: var(--primary);
        }
        
        table {
            width: 100%;
            border-collapse: collapse;
            margin: 20px 0;
            box-shadow: 0 2px 5px rgba(0,0,0,0.05);
        }
        
        th {
            background-color: var(--primary);
            color: white;
            padding: 12px 15px;
            text-align: left;
            font-weight: 600;
        }
        
        td {
            padding: 12px 15px;
            border-bottom: 1px solid #e0e0e0;
        }
        
        tr:nth-child(even) {
            background-color: #f9f9f9;
        }
        
        tr:hover {
            background-color: #f1f8ff;
        }
        
        .property-card {
            background: #f8f9fa;
            border-left: 4px solid var(--secondary);
            padding: 15px;
            margin: 15px 0;
            border-radius: 0 5px 5px 0;
        }
        
        .comparison-chart {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 20px;
            margin: 25px 0;
        }
        
        .material-card {
            background: white;
            border-radius: 8px;
            padding: 20px;
            box-shadow: 0 3px 8px rgba(0,0,0,0.08);
            border-top: 4px solid;
        }
        
        .conductor-card {
            border-top-color: var(--secondary);
        }
        
        .semiconductor-card {
            border-top-color: var(--success);
        }
        
        .insulator-card {
            border-top-color: var(--warning);
        }
        
        .material-card h4 {
            margin-top: 0;
            font-size: 1.3rem;
        }
        
        .material-card ul {
            padding-left: 20px;
        }
        
        .decision-tree {
            background: #e8f4ff;
            border-radius: 8px;
            padding: 20px;
            margin: 25px 0;
            border-left: 4px solid var(--secondary);
        }
        
        .tree-node {
            margin: 15px 0;
            padding-left: 20px;
            position: relative;
        }
        
        .tree-node::before {
            content: "→";
            position: absolute;
            left: 0;
            color: var(--secondary);
            font-weight: bold;
        }
        
        .conclusion {
            background: linear-gradient(135deg, #f8f9fa, #e8f4ff);
            border-radius: 8px;
            padding: 25px;
            margin-top: 20px;
        }
        
        .trends {
            display: flex;
            flex-wrap: wrap;
            gap: 20px;
            margin-top: 20px;
        }
        
        .trend-card {
            flex: 1;
            min-width: 250px;
            background: white;
            border-radius: 8px;
            padding: 20px;
            box-shadow: 0 3px 8px rgba(0,0,0,0.08);
            border-top: 4px solid var(--accent);
        }
        
        .trend-card h4 {
            color: var(--accent);
        }
        
        footer {
            text-align: center;
            margin-top: 40px;
            padding: 20px;
            color: #7f8c8d;
            font-size: 0.9rem;
            border-top: 1px solid #eee;
        }
        
        @media (max-width: 768px) {
            .comparison-chart, .trends {
                grid-template-columns: 1fr;
            }
            
            h1 {
                font-size: 2rem;
            }
            
            h2 {
                font-size: 1.5rem;
            }
        }