* {
            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;
            min-height: 100vh;
            display: flex;
            flex-direction: column;
        }
        
        header {
            background: linear-gradient(135deg, #6a11cb 0%, #2575fc 100%);
            color: white;
            padding: 2rem 1rem;
            text-align: center;
            box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
        }
        
        .header-content {
            max-width: 1200px;
            margin: 0 auto;
        }
        
        h1 {
            font-size: 2.5rem;
            margin-bottom: 0.5rem;
        }
        
        .subtitle {
            font-size: 1.2rem;
            font-weight: 300;
            max-width: 800px;
            margin: 0 auto;
        }
        
        nav {
            background-color: white;
            box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
        }
        
        .nav-container {
            max-width: 1200px;
            margin: 0 auto;
            display: flex;
            justify-content: center;
        }
        
        .nav-menu {
            display: flex;
            list-style: none;
        }
        
        .nav-menu li {
            padding: 1rem 1.5rem;
        }
        
        .nav-menu a {
            text-decoration: none;
            color: #444;
            font-weight: 500;
            transition: color 0.3s;
        }
        
        .nav-menu a:hover {
            color: #2575fc;
        }
        
        main {
            flex: 1;
            padding: 2rem 1rem;
            max-width: 1200px;
            margin: 0 auto;
            width: 100%;
        }
        
        .intro {
            text-align: center;
            margin-bottom: 2.5rem;
            padding: 0 1rem;
        }
        
        .intro p {
            font-size: 1.1rem;
            color: #555;
            max-width: 800px;
            margin: 0 auto;
        }
        
        .categories {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 2rem;
            margin-bottom: 3rem;
        }
        
        .category-card {
            background: white;
            border-radius: 12px;
            padding: 1.5rem;
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.08);
            transition: transform 0.3s ease, box-shadow 0.3s ease;
        }
        
        .category-card:hover {
            transform: translateY(-5px);
            box-shadow: 0 8px 25px rgba(0, 0, 0, 0.12);
        }
        
        .category-card h3 {
            color: #2c3e50;
            margin-bottom: 1rem;
            font-size: 1.5rem;
            border-bottom: 2px solid #6a11cb;
            padding-bottom: 0.5rem;
        }
        
        .category-card p {
            color: #666;
        }
        
        .category-card ul {
            list-style-type: none;
            margin-top: 1rem;
        }
        
        .category-card li {
            padding: 0.3rem 0;
            color: #444;
        }
        
        .category-card li:before {
            content: "•";
            color: #6a11cb;
            display: inline-block;
            width: 1em;
            margin-left: -1em;
        }
        
        footer {
            background-color: #2c3e50;
            color: #ecf0f1;
            text-align: center;
            padding: 1.5rem;
            margin-top: auto;
        }
        
        .footer-content {
            max-width: 1200px;
            margin: 0 auto;
        }
        
        .beian-info {
            font-size: 0.9rem;
            margin-top: 1rem;
            padding: 0.8rem;
            background-color: rgba(0, 0, 0, 0.2);
            border-radius: 6px;
            display: inline-block;
        }
        
        .beian-link {
            color: #ecf0f1;
            text-decoration: none;
            font-weight: bold;
            display: inline-flex;
            align-items: center;
            padding: 0.3rem 0.6rem;
            background-color: #6a11cb;
            border-radius: 4px;
            margin: 0 0.3rem;
            transition: background-color 0.3s;
        }
        
        .beian-link:hover {
            background-color: #2575fc;
            text-decoration: underline;
        }
        
        .footer-note {
            margin-top: 1rem;
            font-size: 0.9rem;
            color: #bdc3c7;
            max-width: 800px;
            margin-left: auto;
            margin-right: auto;
        }
        
        @media (max-width: 768px) {
            h1 {
                font-size: 2rem;
            }
            
            .subtitle {
                font-size: 1rem;
            }
            
            .nav-menu {
                flex-wrap: wrap;
                justify-content: center;
            }
            
            .nav-menu li {
                padding: 0.8rem 1rem;
            }
            
            .categories {
                grid-template-columns: 1fr;
            }
            
            .category-card {
                padding: 1.2rem;
            }
            
            .beian-info {
                font-size: 0.8rem;
                display: block;
                margin: 1rem 0.5rem;
            }
        }
        
        @media (max-width: 480px) {
            header {
                padding: 1.5rem 1rem;
            }
            
            h1 {
                font-size: 1.8rem;
            }
            
            .nav-menu li {
                padding: 0.6rem 0.8rem;
                font-size: 0.9rem;
            }
            
            .intro p {
                font-size: 1rem;
            }
            
            .beian-info {
                font-size: 0.75rem;
                padding: 0.6rem;
            }
            
            .beian-link {
                display: block;
                margin: 0.5rem 0;
                text-align: center;
            }
        }