:root {
            --primary: #5e35b1;
            --primary-light: #9575cd;
            --secondary: #3949ab;
            --accent: #7c4dff;
            --text: #2b2d42;
            --text-light: #546e7a;
            --light-bg: #f5f5f5;
            --card-bg: #ffffff;
            --border-radius: 12px;
            --shadow-sm: 0 2px 8px rgba(0,0,0,0.08);
            --shadow-md: 0 4px 12px rgba(0,0,0,0.1);
            --success: #43a047;
            --warning: #ff9800;
            --info: #2196f3;
            --error: #e53935;
        }

        * {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
        }

        body {
            font-family: system-ui, -apple-system, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
            line-height: 1.6;
            color: var(--text);
            background-color: var(--light-bg);
            padding: 16px;
            position: relative;
        }

        /* 基础链接样式 */
        a {
            color: var(--primary);
            text-decoration: none;
            transition: all 0.2s;
        }

        a:hover {
            color: var(--primary-light);
        }

        /* 导航链接特殊样式 */
        .nav-item {
            background: white;
            padding: 0.6rem 1.2rem;
            border-radius: 2rem;
            font-size: 0.9rem;
            box-shadow: var(--shadow-sm);
            cursor: pointer;
            transition: all 0.2s;
            color: var(--text);
        }

        .nav-item:hover {
            background: var(--primary-light);
            color: white;
        }

        .nav-item.active {
            background: var(--primary);
            color: white;
            font-weight: 500;
        }

        /* 页脚链接特殊样式 */
        footer a {
            display: inline-block;
            color: var(--primary);
            font-weight: 500;
            padding: 0.5rem 1rem;
            border-radius: 2rem;
            margin: 0.5rem 0;
            background-color: rgba(94, 53, 177, 0.1);
            border: 1px solid rgba(94, 53, 177, 0.2);
        }

        footer a:hover {
            color: white;
            background-color: var(--primary);
            transform: translateY(-2px);
            box-shadow: 0 2px 8px rgba(94, 53, 177, 0.2);
        }

        .container {
            max-width: 1000px;
            margin: 0 auto;
        }

        .header-card {
            background: linear-gradient(135deg, var(--primary), var(--secondary));
            color: white;
            padding: 2rem;
            border-radius: var(--border-radius);
            margin-bottom: 2rem;
            box-shadow: var(--shadow-md);
            text-align: center;
            position: relative;
            overflow: hidden;
        }

        .header-card::after {
            content: "";
            position: absolute;
            top: -50px;
            right: -50px;
            width: 200px;
            height: 200px;
            background: rgba(255,255,255,0.1);
            border-radius: 50%;
        }

        .header-card h1 {
            font-size: clamp(1.5rem, 5vw, 2.5rem);
            margin-bottom: 0.5rem;
            position: relative;
            z-index: 1;
            font-weight: 700;
            word-wrap: break-word;
            overflow-wrap: break-word;
        }

        .header-card p {
            opacity: 0.9;
            font-size: 1.1rem;
            position: relative;
            z-index: 1;
        }

        .nav-menu {
            display: flex;
            justify-content: center;
            gap: 1rem;
            margin-bottom: 1.5rem;
            flex-wrap: wrap;
            position: sticky;
            top: 10px;
            z-index: 100;
            background-color: var(--light-bg);
            padding: 10px;
            border-radius: var(--border-radius);
            box-shadow: var(--shadow-sm);
        }

        .card {
            background: var(--card-bg);
            border-radius: var(--border-radius);
            padding: 1.5rem;
            margin-bottom: 1.5rem;
            box-shadow: var(--shadow-sm);
        }

        .card-title {
            color: var(--primary);
            font-size: 1.4rem;
            margin-bottom: 1.2rem;
            padding-bottom: 0.6rem;
            border-bottom: 2px solid rgba(94, 53, 177, 0.15);
            display: flex;
            align-items: center;
            font-weight: 600;
        }

        .card-title .icon {
            margin-right: 0.8rem;
            font-size: 1.5rem;
        }

        .overview-card {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 1.5rem;
        }

        .word-basic {
            display: flex;
            flex-direction: column;
            justify-content: center;
        }

        .word-title {
            font-size: 2rem;
            color: var(--primary);
            margin-bottom: 0.5rem;
            font-weight: 700;
        }

        .word-phonetic {
            display: flex;
            align-items: center;
            margin-bottom: 0.8rem;
        }

        .phonetic {
            font-family: 'Arial Unicode MS', sans-serif;
            font-size: 1.2rem;
            margin-right: 1rem;
        }

        .word-property {
            display: flex;
            gap: 1rem;
            margin-top: 0.5rem;
        }

        .property-tag {
            background: #ede7f6;
            color: var(--primary);
            padding: 0.2rem 0.8rem;
            border-radius: 1rem;
            font-size: 0.8rem;
        }

        .word-translation {
            font-size: 1.1rem;
            line-height: 1.6;
            padding: 1rem;
            background: #f5f5f5;
            border-radius: var(--border-radius);
        }

        .meaning-grid {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
            gap: 1.2rem;
            margin-bottom: 1.5rem;
        }

        .meaning-card {
            background: var(--card-bg);
            border-radius: var(--border-radius);
            padding: 1.2rem;
            box-shadow: var(--shadow-sm);
            border-top: 4px solid var(--accent);
            transition: transform 0.2s;
        }

        .meaning-card:hover {
            transform: translateY(-3px);
        }

        .meaning-card h3 {
            color: var(--secondary);
            margin-bottom: 0.8rem;
            font-size: 1.2rem;
            font-weight: 600;
        }

        .meaning-card p {
            color: var(--text-light);
            font-size: 0.95rem;
            margin-bottom: 0.8rem;
        }

        .example-card {
            background: #f8f9fa;
            border-left: 4px solid var(--info);
            padding: 0.8rem 1rem 0.8rem 1.2rem;
            border-radius: 0 var(--border-radius) var(--border-radius) 0;
            margin: 0.8rem 0;
            position: relative;
            font-size: 0.95rem;
        }

        .example-card::before {
            content: "例";
            position: absolute;
            left: -14px;
            top: 50%;
            transform: translateY(-50%);
            background: var(--info);
            color: white;
            width: 28px;
            height: 28px;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 0.8rem;
            font-weight: bold;
        }

        .tag {
            display: inline-block;
            background: var(--primary-light);
            color: white;
            padding: 0.2rem 0.6rem;
            border-radius: 1rem;
            font-size: 0.75rem;
            margin-right: 0.5rem;
            margin-top: 0.5rem;
        }

        .comparison-card {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 1rem;
            margin: 1.2rem 0;
        }

        .english-example {
            background: #e3f2fd;
            padding: 1rem;
            border-radius: var(--border-radius);
        }

        .chinese-translation {
            background: #e8f5e9;
            padding: 1rem;
            border-radius: var(--border-radius);
        }

        .highlight {
            background-color: #fff9c4;
            padding: 0 0.2rem;
            border-radius: 0.2rem;
        }

        .pronunciation-card {
            background: linear-gradient(to right, #f0f7ff, #d8ebff);
            border-left: 4px solid var(--info);
        }

        .pronunciation-compare {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 1rem;
            margin: 1.2rem 0;
        }

        .pronunciation-type {
            background: white;
            padding: 1rem;
            border-radius: var(--border-radius);
            box-shadow: var(--shadow-sm);
            text-align: center;
        }

        .ipa {
            font-family: 'Arial Unicode MS', sans-serif;
            font-size: 1.3rem;
            color: var(--primary);
            font-weight: bold;
            margin: 0.5rem 0;
        }

        .tip-card {
            background: #fff8e1;
            border-left: 4px solid var(--warning);
            padding: 1rem;
            border-radius: var(--border-radius);
            margin: 1rem 0;
        }

        .tip-card::before {
            content: "💡 顾老师提示";
            display: block;
            font-weight: bold;
            color: var(--warning);
            margin-bottom: 0.5rem;
            font-size: 0.95rem;
        }

        .tip-card p {
            font-size: 0.95rem;
            color: var(--text);
        }

        .practice-card {
            background: #f0f9f0;
            border-left: 4px solid var(--success);
        }

        .exercise {
            margin-bottom: 1.5rem;
        }

        .exercise h3 {
            color: var(--success);
            margin-bottom: 0.8rem;
            font-size: 1.1rem;
            display: flex;
            align-items: center;
        }

        .exercise h3::before {
            content: "✍️";
            margin-right: 0.6rem;
            font-size: 1rem;
        }

        .grammar-forms {
            display: flex;
            flex-wrap: wrap;
            gap: 0.8rem;
            margin-top: 1rem;
        }

        .grammar-form {
            background: white;
            padding: 0.6rem 1rem;
            border-radius: 1.5rem;
            font-size: 0.9rem;
            box-shadow: var(--shadow-sm);
            display: flex;
            align-items: center;
        }

        .grammar-form strong {
            color: var(--primary);
            margin-right: 0.3rem;
        }

        .show-answer {
            background: var(--primary);
            color: white;
            border: none;
            padding: 0.6rem 1.2rem;
            border-radius: 0.3rem;
            margin-top: 0.8rem;
            cursor: pointer;
            transition: all 0.2s;
        }

        .show-answer:hover {
            background: var(--primary-light);
        }

        .answer {
            margin-top: 1rem;
            padding: 1rem;
            background: #e8f5e9;
            border-radius: var(--border-radius);
            display: none;
        }

        .footer {
            text-align: center;
            margin-top: 2.5rem;
            color: var(--text-light);
            font-size: 0.9rem;
            padding: 1rem 0;
            border-top: 1px solid rgba(0,0,0,0.1);
        }

        .pronunciation-list {
            padding-left: 1.2rem;
            margin-bottom: 1rem;
        }

        .pronunciation-list li {
            margin-bottom: 0.4rem;
        }

        .mb-1 { margin-bottom: 0.5rem; }
        .mb-2 { margin-bottom: 1rem; }
        .mt-2 { margin-top: 1rem; }
        .text-center { text-align: center; }
        
        .section-anchor {
            scroll-margin-top: 80px;
        }

        @media (max-width: 768px) {
            .overview-card {
                grid-template-columns: 1fr;
            }
            
            .pronunciation-compare,
            .comparison-card {
                grid-template-columns: 1fr;
            }
            
            .header-card {
                padding: 1.5rem;
            }
            
            .card {
                padding: 1.2rem;
            }
        }

        @media (max-width: 480px) {
            .meaning-grid {
                grid-template-columns: 1fr;
            }
            
            .nav-menu {
                gap: 0.5rem;
            }
            
            .nav-item {
                padding: 0.4rem 0.8rem;
                font-size: 0.8rem;
            }

            footer a {
                padding: 0.4rem 0.8rem;
                font-size: 0.85rem;
            }
        }