:root {
            --primary-color: #2563eb;
            --secondary-color: #7c3aed;
            --accent-color: #06b6d4;
            --dark-bg: #1e293b;
            --light-bg: #f8fafc;
        }
        
        body {
            font-family: 'Roboto', sans-serif;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            min-height: 100vh;
        }
        
        h1, h2, h3, h4 {
            font-family: 'Poppins', sans-serif;
        }
        .hero-title {
          font-size: 4rem;
          font-weight: 800;
        }
        .hero-section {
            background: linear-gradient(135deg, rgba(37, 99, 235, 0.9) 0%, rgba(124, 58, 237, 0.9) 100%);
            color: white;
            padding: 60px 0;
            margin-bottom: 40px;
            box-shadow: 0 10px 30px rgba(0,0,0,0.3);
        }
        
        .hero-section h1 {
            font-weight: 700;
            font-size: 3rem;
            margin-bottom: 20px;
            text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
        }
    
        
        .hero-section p {
            font-size: 1.2rem;
            opacity: 0.95;
        }
        
        .level-section {
            margin-bottom: 50px;
        }
        
        .level-jumbotron {
            background: white;
            border-radius: 20px;
            padding: 40px;
            box-shadow: 0 10px 40px rgba(0,0,0,0.15);
            transition: transform 0.3s ease, box-shadow 0.3s ease;
            margin-bottom: 30px;
        }
        
        .level-jumbotron:hover {
            transform: translateY(-5px);
            box-shadow: 0 15px 50px rgba(0,0,0,0.25);
        }
        
        .level-header {
            display: flex;
            align-items: center;
            margin-bottom: 25px;
            padding-bottom: 20px;
            border-bottom: 3px solid;
        }
        
        .level-1 .level-header { border-color: #10b981; }
        .level-2 .level-header { border-color: #3b82f6; }
        .level-3 .level-header { border-color: #f59e0b; }
        .level-4 .level-header { border-color: #ef4444; }
        
        .level-icon {
            font-size: 3rem;
            margin-right: 20px;
            width: 80px;
            height: 80px;
            display: flex;
            align-items: center;
            justify-content: center;
            border-radius: 15px;
            color: white;
        }
        
        .level-1 .level-icon { background: linear-gradient(135deg, #10b981, #059669); }
        .level-2 .level-icon { background: linear-gradient(135deg, #3b82f6, #2563eb); }
        .level-3 .level-icon { background: linear-gradient(135deg, #f59e0b, #d97706); }
        .level-4 .level-icon { background: linear-gradient(135deg, #ef4444, #dc2626); }
        
        .level-title h2 {
            margin: 0;
            font-weight: 700;
            font-size: 2rem;
        }
        
        .level-subtitle {
            color: #64748b;
            font-size: 1.1rem;
            margin-top: 5px;
        }
        
        .lesson-grid {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
            gap: 20px;
        }
        
        .lesson-card {
            background: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%);
            border-radius: 12px;
            padding: 20px;
            transition: all 0.3s ease;
            cursor: pointer;
            border: 2px solid transparent;
            text-decoration: none;
            color: inherit;
            display: block;
        }
        
        .lesson-card:hover {
            transform: translateY(-3px);
            border-color: var(--primary-color);
            background: white;
            box-shadow: 0 8px 25px rgba(37, 99, 235, 0.2);
        }
        
        .lesson-number {
            display: inline-block;
            background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
            color: white;
            width: 35px;
            height: 35px;
            border-radius: 50%;
            text-align: center;
            line-height: 35px;
            font-weight: 600;
            margin-bottom: 10px;
            font-size: 0.9rem;
        }
        
        .lesson-title {
            font-weight: 600;
            font-size: 1.1rem;
            color: #1e293b;
            margin: 0;
        }
        
        .lesson-icon {
            float: right;
            color: var(--primary-color);
            font-size: 1.5rem;
            opacity: 0.5;
            transition: opacity 0.3s ease;
        }
        
        .lesson-card:hover .lesson-icon {
            opacity: 1;
        }
        
        @media (max-width: 768px) {
            .hero-section h1 {
                font-size: 2rem;
            }
            
            .level-header {
                flex-direction: column;
                text-align: center;
            }
            
            .level-icon {
                margin-right: 0;
                margin-bottom: 15px;
            }
            
            .lesson-grid {
                grid-template-columns: 1fr;
            }
        }
        
        .badge-level {
            font-size: 0.8rem;
            padding: 5px 12px;
            border-radius: 20px;
            margin-left: 10px;
        }