* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }
        
        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
            line-height: 1.6;
            color: #2c3e50;
            background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
            min-height: 100vh;
            margin: 0;
            padding: 2rem;
        }
        
        .container {
            max-width: 1200px;
            margin: 0 auto;
            background: white;
            padding: 3rem;
            border-radius: 20px;
            box-shadow: 0 15px 35px rgba(0,0,0,0.1);
        }
        
        .header {
            text-align: center;
            margin-bottom: 3rem;
            padding-bottom: 2rem;
            border-bottom: 2px solid #f1f3f4;
        }
        
        .header h1 {
            font-size: 2.5rem;
            color: #2c3e50;
            margin-bottom: 1rem;
            background: linear-gradient(135deg, #667eea, #764ba2);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            background-clip: text;
        }
        
        .header p {
            font-size: 1.1rem;
            color: #7f8c8d;
            max-width: 700px;
            margin: 0 auto 2rem;
        }
        
        .learning-paths-intro {
            background: linear-gradient(135deg, #667eea10, #764ba210);
            padding: 2rem;
            border-radius: 15px;
            margin: 2rem 0;
            border: 1px solid #667eea20;
        }
        
        .learning-paths-intro h3 {
            color: #667eea;
            margin-bottom: 1rem;
            font-size: 1.3rem;
        }
        
        .clusters-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
            gap: 2rem;
            margin-bottom: 3rem;
        }
        
        .cluster {
            background: linear-gradient(135deg, #ffffff, #f8f9fa);
            border: 2px solid transparent;
            border-radius: 15px;
            padding: 2rem;
            transition: all 0.3s ease;
            position: relative;
            overflow: hidden;
        }
        
        .cluster::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            border-radius: 15px;
            padding: 2px;
            background: linear-gradient(135deg, #667eea, #764ba2);
            mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
            mask-composite: xor;
            -webkit-mask-composite: xor;
            opacity: 0;
            transition: opacity 0.3s ease;
        }
        
        .cluster:hover::before {
            opacity: 1;
        }
        
        .cluster:hover {
            transform: translateY(-8px);
            box-shadow: 0 20px 40px rgba(102, 126, 234, 0.2);
        }
        
        .cluster-header {
            margin-bottom: 1.5rem;
        }
        
        .cluster h2 {
            color: #2c3e50;
            font-size: 1.4rem;
            margin-bottom: 0.5rem;
            display: flex;
            align-items: center;
            gap: 0.5rem;
        }
        
        .cluster-icon {
            width: 40px;
            height: 40px;
            background: linear-gradient(135deg, #667eea, #764ba2);
            border-radius: 10px;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 1.2rem;
            color: white;
        }
        
        .cluster-description {
            color: #7f8c8d;
            font-size: 0.95rem;
            line-height: 1.5;
        }
        
        .cluster-meta {
            display: flex;
            justify-content: space-between;
            margin: 1rem 0;
            padding: 1rem;
            background: rgba(102, 126, 234, 0.05);
            border-radius: 8px;
        }
        
        .meta-item {
            text-align: center;
        }
        
        .meta-label {
            font-size: 0.8rem;
            color: #7f8c8d;
            margin-bottom: 0.3rem;
        }
        
        .meta-value {
            font-weight: 600;
            color: #667eea;
            font-size: 0.9rem;
        }
        
        .cluster-links {
            list-style: none;
            padding: 0;
        }
        
        .cluster-links li {
            margin-bottom: 0.8rem;
            padding-left: 1rem;
            position: relative;
        }
        
        .cluster-links li::before {
            content: '▶';
            position: absolute;
            left: 0;
            color: #667eea;
            font-size: 0.8rem;
        }
        
        .cluster-links a {
            color: #2c3e50;
            text-decoration: none;
            font-weight: 500;
            transition: all 0.2s ease;
            line-height: 1.4;
        }
        
        .cluster-links a:hover {
            color: #667eea;
            text-decoration: underline;
        }
        
        .learning-tips {
            background: linear-gradient(135deg, #f8f9fa, #ffffff);
            padding: 2rem;
            border-radius: 15px;
            margin: 3rem 0;
            border: 1px solid #e9ecef;
        }
        
        .learning-tips h3 {
            color: #2c3e50;
            margin-bottom: 1rem;
            display: flex;
            align-items: center;
            gap: 0.5rem;
        }
        
        .tips-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
            gap: 1.5rem;
            margin-top: 1.5rem;
        }
        
        .tip {
            padding: 1rem;
            background: white;
            border-radius: 8px;
            border-left: 4px solid #667eea;
        }
        
        .tip-title {
            font-weight: 600;
            color: #2c3e50;
            margin-bottom: 0.5rem;
        }
        
        .back-nav {
            text-align: center;
            margin: 3rem 0;
            padding-top: 2rem;
            border-top: 2px solid #f1f3f4;
        }
        
        .back-nav a {
            display: inline-flex;
            align-items: center;
            gap: 0.5rem;
            padding: 1rem 2rem;
            background: linear-gradient(135deg, #667eea, #764ba2);
            color: white;
            text-decoration: none;
            border-radius: 25px;
            font-weight: 600;
            transition: all 0.3s ease;
        }
        
        .back-nav a:hover {
            transform: translateY(-2px);
            box-shadow: 0 10px 25px rgba(102, 126, 234, 0.3);
        }
        
        @media (max-width: 768px) {
            body {
                padding: 1rem;
            }
            
            .container {
                padding: 2rem;
            }
            
            .header h1 {
                font-size: 2rem;
            }
            
            .clusters-grid {
                grid-template-columns: 1fr;
            }
            
            .cluster-meta {
                flex-direction: column;
                gap: 1rem;
            }
            
            .tips-grid {
                grid-template-columns: 1fr;
            }
        }