* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }
        :root {
            --primary: #1a365d;
            --secondary: #2d3748;
            --accent: #38b2ac;
            --light: #f7fafc;
            --dark: #1a202c;
            --gray: #718096;
            --border: #e2e8f0;
            --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
            --transition: all 0.3s ease;
        }
        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
            line-height: 1.6;
            color: var(--dark);
            background-color: var(--light);
            font-size: 16px;
        }
        h1, h2, h3, h4 {
            color: var(--primary);
            font-weight: 700;
            line-height: 1.2;
            margin-bottom: 1rem;
        }
        h1 {
            font-size: 2.5rem;
            border-bottom: 3px solid var(--accent);
            padding-bottom: 0.5rem;
        }
        h2 {
            font-size: 1.8rem;
            margin-top: 2rem;
            padding-left: 0.5rem;
            border-left: 4px solid var(--accent);
        }
        h3 {
            font-size: 1.4rem;
            margin-top: 1.5rem;
            color: var(--secondary);
        }
        h4 {
            font-size: 1.1rem;
            color: var(--gray);
        }
        p {
            margin-bottom: 1rem;
            max-width: 80ch;
        }
        a {
            color: var(--primary);
            text-decoration: none;
            transition: var(--transition);
        }
        a:hover {
            color: var(--accent);
            text-decoration: underline;
        }
        .container {
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 1.5rem;
        }
        header {
            background: linear-gradient(135deg, var(--primary) 0%, var(--dark) 100%);
            color: white;
            padding: 1rem 0;
            position: sticky;
            top: 0;
            z-index: 1000;
            box-shadow: var(--shadow);
        }
        .header-content {
            display: flex;
            justify-content: space-between;
            align-items: center;
        }
        .logo {
            font-size: 1.8rem;
            font-weight: 800;
            display: flex;
            align-items: center;
            gap: 0.5rem;
        }
        .logo a {
            color: white;
        }
        .logo a:hover {
            text-decoration: none;
            color: var(--accent);
        }
        nav ul {
            display: flex;
            list-style: none;
            gap: 2rem;
        }
        nav a {
            color: white;
            font-weight: 500;
            padding: 0.5rem 1rem;
            border-radius: 4px;
            transition: var(--transition);
        }
        nav a:hover, nav a.active {
            background: rgba(255, 255, 255, 0.1);
            text-decoration: none;
        }
        .hamburger {
            display: none;
            font-size: 1.5rem;
            background: none;
            border: none;
            color: white;
            cursor: pointer;
            padding: 0.5rem;
        }
        main {
            padding: 2rem 0;
            display: grid;
            grid-template-columns: 1fr 300px;
            gap: 2rem;
        }
        .content {
            background: white;
            padding: 2rem;
            border-radius: 8px;
            box-shadow: var(--shadow);
        }
        aside {
            background: white;
            padding: 1.5rem;
            border-radius: 8px;
            box-shadow: var(--shadow);
            align-self: start;
            position: sticky;
            top: 100px;
        }
        .info-box {
            background: #f8f9fa;
            border: 1px solid var(--border);
            border-radius: 6px;
            padding: 1.5rem;
            margin-bottom: 1.5rem;
        }
        .info-box h3 {
            margin-top: 0;
            border-bottom: 2px solid var(--accent);
            padding-bottom: 0.5rem;
        }
        table {
            width: 100%;
            border-collapse: collapse;
            margin: 1.5rem 0;
            background: white;
            box-shadow: 0 1px 3px rgba(0,0,0,0.1);
        }
        th, td {
            padding: 0.75rem 1rem;
            text-align: left;
            border-bottom: 1px solid var(--border);
        }
        th {
            background: var(--primary);
            color: white;
            font-weight: 600;
        }
        tr:hover {
            background: #f8f9fa;
        }
        .article-image {
            width: 100%;
            height: auto;
            border-radius: 8px;
            margin: 1.5rem 0;
            box-shadow: var(--shadow);
            object-fit: cover;
        }
        .image-caption {
            text-align: center;
            font-style: italic;
            color: var(--gray);
            margin-top: -0.5rem;
            margin-bottom: 1.5rem;
        }
        form {
            background: #f8f9fa;
            padding: 1.5rem;
            border-radius: 8px;
            margin: 1.5rem 0;
        }
        .form-group {
            margin-bottom: 1rem;
        }
        label {
            display: block;
            margin-bottom: 0.5rem;
            font-weight: 600;
        }
        input, select, textarea {
            width: 100%;
            padding: 0.75rem;
            border: 1px solid var(--border);
            border-radius: 4px;
            font-size: 1rem;
        }
        textarea {
            min-height: 150px;
            resize: vertical;
        }
        button, .btn {
            background: var(--primary);
            color: white;
            border: none;
            padding: 0.75rem 1.5rem;
            border-radius: 4px;
            cursor: pointer;
            font-weight: 600;
            transition: var(--transition);
            display: inline-block;
            text-align: center;
            min-width: 44px;
            min-height: 44px;
        }
        button:hover, .btn:hover {
            background: var(--accent);
            transform: translateY(-2px);
            text-decoration: none;
        }
        .rating {
            display: flex;
            gap: 0.5rem;
            margin: 1rem 0;
        }
        .star {
            color: #e2e8f0;
            cursor: pointer;
            font-size: 1.5rem;
            transition: var(--transition);
        }
        .star.active, .star:hover {
            color: #fbbf24;
        }
        .comment {
            background: white;
            padding: 1rem;
            border-radius: 6px;
            margin-bottom: 1rem;
            border: 1px solid var(--border);
        }
        .comment-header {
            display: flex;
            justify-content: space-between;
            margin-bottom: 0.5rem;
            font-size: 0.9rem;
            color: var(--gray);
        }
        .social-share {
            display: flex;
            gap: 1rem;
            margin: 2rem 0;
        }
        .share-btn {
            display: flex;
            align-items: center;
            gap: 0.5rem;
            padding: 0.5rem 1rem;
            background: #f8f9fa;
            border-radius: 4px;
        }
        #backToTop {
            position: fixed;
            bottom: 2rem;
            right: 2rem;
            background: var(--primary);
            color: white;
            width: 50px;
            height: 50px;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            cursor: pointer;
            opacity: 0;
            transition: var(--transition);
            z-index: 999;
        }
        #backToTop.visible {
            opacity: 1;
        }
        footer {
            background: var(--dark);
            color: white;
            padding: 3rem 0 1.5rem;
            margin-top: 3rem;
        }
        .footer-content {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
            gap: 2rem;
            margin-bottom: 2rem;
        }
        .footer-section h3 {
            color: white;
            margin-bottom: 1rem;
        }
        .footer-links {
            list-style: none;
        }
        .footer-links li {
            margin-bottom: 0.5rem;
        }
        .footer-links a {
            color: #cbd5e0;
        }
        .footer-links a:hover {
            color: white;
        }
        friend-link {
            display: block;
            margin: 1rem 0;
            padding: 0.5rem;
            background: rgba(255,255,255,0.1);
            border-radius: 4px;
        }
        .copyright {
            text-align: center;
            padding-top: 1.5rem;
            border-top: 1px solid #4a5568;
            color: #a0aec0;
            font-size: 0.9rem;
        }
        @media (max-width: 1024px) {
            main {
                grid-template-columns: 1fr;
            }
            aside {
                position: static;
            }
        }
        @media (max-width: 768px) {
            .header-content {
                flex-wrap: wrap;
            }
            nav {
                width: 100%;
                order: 3;
                margin-top: 1rem;
                display: none;
            }
            nav.active {
                display: block;
            }
            nav ul {
                flex-direction: column;
                gap: 0.5rem;
            }
            .hamburger {
                display: block;
            }
            h1 {
                font-size: 2rem;
            }
            h2 {
                font-size: 1.5rem;
            }
            .content {
                padding: 1.5rem;
            }
            .social-share {
                flex-wrap: wrap;
            }
        }
        @media (max-width: 480px) {
            .container {
                padding: 0 1rem;
            }
            .content {
                padding: 1rem;
            }
            button, .btn {
                padding: 0.75rem 1rem;
                font-size: 0.9rem;
            }
        }
        .highlight {
            background: #fffbeb;
            border-left: 4px solid #fbbf24;
            padding: 1rem;
            margin: 1rem 0;
            border-radius: 0 4px 4px 0;
        }
        .tip {
            background: #f0fff4;
            border-left: 4px solid #48bb78;
            padding: 1rem;
            margin: 1rem 0;
            border-radius: 0 4px 4px 0;
        }
        .note {
            background: #ebf8ff;
            border-left: 4px solid #4299e1;
            padding: 1rem;
            margin: 1rem 0;
            border-radius: 0 4px 4px 0;
        }
        .badge {
            display: inline-block;
            padding: 0.25rem 0.5rem;
            background: var(--accent);
            color: white;
            border-radius: 4px;
            font-size: 0.8rem;
            font-weight: 600;
            margin-right: 0.5rem;
        }
        .last-updated {
            font-size: 0.9rem;
            color: var(--gray);
            margin-bottom: 1rem;
            display: flex;
            align-items: center;
            gap: 0.5rem;
        }
        .content-section {
            margin-bottom: 2.5rem;
            padding-bottom: 2rem;
            border-bottom: 1px solid var(--border);
        }
        .content-section:last-child {
            border-bottom: none;
        }
        .two-column {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 2rem;
            margin: 1.5rem 0;
        }
        .feature-list {
            list-style: none;
        }
        .feature-list li {
            padding: 0.5rem 0;
            border-bottom: 1px solid var(--border);
            display: flex;
            align-items: center;
            gap: 0.5rem;
        }
        .feature-list li:before {
            content: "✓";
            color: var(--accent);
            font-weight: bold;
        }