:root {
            --primary: #1a73e8;
            --secondary: #0d47a1;
            --accent: #e8f0fe;
            --text-dark: #202124;
            --text-light: #5f6368;
            --bg-light: #f8f9fa;
            --bg-white: #ffffff;
            --border: #dadce0;
            --shadow: rgba(0, 0, 0, 0.1);
            --success: #34a853;
            --warning: #f9ab00;
        }
        * { margin: 0; padding: 0; box-sizing: border-box; }
        html { scroll-behavior: smooth; }
        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
            color: var(--text-dark);
            background-color: var(--bg-light);
            line-height: 1.6;
        }
        img { max-width: 100%; height: auto; display: block; }
        a { color: var(--primary); text-decoration: none; transition: color 0.3s; }
        a:hover { color: var(--secondary); }
        .container { width: 100%; max-width: 1200px; margin: 0 auto; padding: 0 20px; }
        .site-header {
            background: var(--bg-white);
            box-shadow: 0 2px 10px var(--shadow);
            position: sticky;
            top: 0;
            z-index: 1000;
        }
        .header-top {
            display: flex;
            justify-content: space-between;
            align-items: center;
            padding: 15px 0;
        }
        .my-logo {
            font-size: 1.8rem;
            font-weight: 700;
            color: var(--primary);
            display: flex;
            align-items: center;
            gap: 10px;
        }
        .my-logo:hover { color: var(--secondary); }
        .my-logo i { color: var(--warning); }
        .search-form {
            display: flex;
            max-width: 400px;
            flex-grow: 1;
            margin: 0 30px;
        }
        .search-form input {
            flex-grow: 1;
            padding: 10px 15px;
            border: 1px solid var(--border);
            border-radius: 24px 0 0 24px;
            font-size: 1rem;
        }
        .search-form button {
            background: var(--primary);
            color: white;
            border: none;
            padding: 10px 20px;
            border-radius: 0 24px 24px 0;
            cursor: pointer;
            transition: background 0.3s;
        }
        .search-form button:hover { background: var(--secondary); }
        .mobile-toggle {
            display: none;
            background: none;
            border: none;
            font-size: 1.5rem;
            color: var(--text-dark);
            cursor: pointer;
        }
        .main-nav {
            background: var(--secondary);
            padding: 0 20px;
        }
        .nav-list {
            list-style: none;
            display: flex;
            justify-content: center;
            flex-wrap: wrap;
        }
        .nav-list li { position: relative; }
        .nav-list a {
            color: white;
            display: block;
            padding: 15px 20px;
            font-weight: 500;
        }
        .nav-list a:hover {
            background: rgba(255, 255, 255, 0.1);
            color: white;
        }
        .breadcrumb {
            padding: 12px 20px;
            background: var(--accent);
            font-size: 0.9rem;
            color: var(--text-light);
        }
        .breadcrumb a { color: var(--text-light); }
        .breadcrumb a:hover { color: var(--primary); }
        .main-content {
            display: grid;
            grid-template-columns: 1fr 300px;
            gap: 40px;
            padding: 40px 0;
        }
        .article-content {
            background: var(--bg-white);
            padding: 40px;
            border-radius: 12px;
            box-shadow: 0 4px 12px var(--shadow);
        }
        .sidebar {
            background: var(--bg-white);
            padding: 25px;
            border-radius: 12px;
            box-shadow: 0 4px 12px var(--shadow);
            align-self: start;
            position: sticky;
            top: 140px;
        }
        .sidebar h3 {
            margin-bottom: 20px;
            padding-bottom: 10px;
            border-bottom: 2px solid var(--primary);
            color: var(--secondary);
        }
        .sidebar ul {
            list-style: none;
            margin-bottom: 25px;
        }
        .sidebar li { margin-bottom: 12px; }
        .sidebar a { display: block; padding: 5px 0; }
        h1 {
            font-size: 2.8rem;
            color: var(--secondary);
            margin-bottom: 25px;
            line-height: 1.2;
        }
        h2 {
            font-size: 2rem;
            color: var(--secondary);
            margin: 40px 0 20px;
            padding-bottom: 10px;
            border-bottom: 1px solid var(--border);
        }
        h3 {
            font-size: 1.6rem;
            color: var(--primary);
            margin: 30px 0 15px;
        }
        h4 {
            font-size: 1.3rem;
            color: var(--text-dark);
            margin: 25px 0 10px;
        }
        p {
            margin-bottom: 1.5em;
            text-align: justify;
        }
        .lead {
            font-size: 1.2rem;
            color: var(--text-light);
            font-weight: 500;
            margin-bottom: 30px;
        }
        .highlight {
            background: var(--accent);
            border-left: 4px solid var(--primary);
            padding: 20px;
            margin: 25px 0;
            border-radius: 0 8px 8px 0;
        }
        .emoji { margin-right: 8px; }
        b, strong { color: var(--text-dark); }
        .related-link {
            display: inline-block;
            background: var(--accent);
            color: var(--primary);
            padding: 8px 15px;
            border-radius: 20px;
            margin: 5px 10px 5px 0;
            font-weight: 500;
        }
        .related-link:hover {
            background: var(--primary);
            color: white;
        }
        .figure-container {
            margin: 30px 0;
            text-align: center;
        }
        .figure-container img {
            border-radius: 12px;
            box-shadow: 0 6px 16px var(--shadow);
            margin: 0 auto 15px;
        }
        .figcaption {
            font-style: italic;
            color: var(--text-light);
            font-size: 0.95rem;
        }
        .update-time {
            display: inline-block;
            background: var(--warning);
            color: white;
            padding: 5px 15px;
            border-radius: 15px;
            font-size: 0.9rem;
            margin-bottom: 30px;
        }
        .interactive-section {
            background: var(--bg-light);
            padding: 30px;
            border-radius: 12px;
            margin: 40px 0;
        }
        .interactive-section h3 { margin-top: 0; }
        .form-group {
            margin-bottom: 20px;
        }
        .form-group label {
            display: block;
            margin-bottom: 8px;
            font-weight: 600;
        }
        .form-control {
            width: 100%;
            padding: 12px 15px;
            border: 1px solid var(--border);
            border-radius: 8px;
            font-size: 1rem;
            transition: border 0.3s;
        }
        .form-control:focus {
            outline: none;
            border-color: var(--primary);
            box-shadow: 0 0 0 3px rgba(26, 115, 232, 0.2);
        }
        textarea.form-control { min-height: 120px; resize: vertical; }
        .btn {
            background: var(--primary);
            color: white;
            border: none;
            padding: 12px 25px;
            border-radius: 8px;
            cursor: pointer;
            font-size: 1rem;
            font-weight: 600;
            transition: background 0.3s, transform 0.2s;
        }
        .btn:hover {
            background: var(--secondary);
            transform: translateY(-2px);
        }
        .rating {
            display: flex;
            gap: 10px;
            align-items: center;
            flex-wrap: wrap;
        }
        .rating input { display: none; }
        .rating label {
            font-size: 1.8rem;
            color: var(--border);
            cursor: pointer;
            transition: color 0.2s;
        }
        .rating input:checked ~ label,
        .rating label:hover,
        .rating label:hover ~ label { color: var(--warning); }
        .site-footer {
            background: var(--text-dark);
            color: white;
            padding: 50px 0 30px;
            margin-top: 60px;
        }
        .footer-content {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
            gap: 40px;
            margin-bottom: 40px;
        }
        .footer-logo {
            font-size: 1.8rem;
            font-weight: 700;
            margin-bottom: 20px;
            color: white;
        }
        .footer-nav h4 {
            color: white;
            margin-bottom: 20px;
            font-size: 1.2rem;
        }
        .footer-nav ul { list-style: none; }
        .footer-nav li { margin-bottom: 12px; }
        .footer-nav a { color: #bdc1c6; }
        .footer-nav a:hover { color: white; }
        friend-link {
            display: block;
            background: rgba(255, 255, 255, 0.05);
            padding: 15px;
            border-radius: 8px;
            margin-bottom: 15px;
            color: #bdc1c6;
        }
        friend-link a { color: #bdc1c6; }
        friend-link a:hover { color: white; }
        .copyright {
            text-align: center;
            padding-top: 30px;
            border-top: 1px solid rgba(255, 255, 255, 0.1);
            color: #9aa0a6;
            font-size: 0.9rem;
        }
        @media (max-width: 992px) {
            .main-content { grid-template-columns: 1fr; }
            .sidebar { position: static; }
            h1 { font-size: 2.4rem; }
        }
        @media (max-width: 768px) {
            .header-top { flex-wrap: wrap; }
            .search-form { order: 3; width: 100%; margin: 15px 0 0; }
            .mobile-toggle { display: block; }
            .main-nav { display: none; padding: 0; }
            .main-nav.active { display: block; }
            .nav-list { flex-direction: column; }
            .nav-list a { padding: 15px; border-bottom: 1px solid rgba(255,255,255,0.1); }
            .article-content { padding: 25px; }
            .footer-content { grid-template-columns: 1fr; }
        }