/* css/topic.css - 知识点页面样式 - 蓝粉渐变主题 */

/* 添加自定义字体 */
@font-face {
    font-family: 'MyCustomFont';
    src: url('../font/13.woff2') format('woff2');
    font-weight: normal;
    font-style: normal;
    font-display: swap;
}

:root {
    /* 蓝色系 */
    --blue-primary: #4A90E2;
    --blue-light: #6BB0FF;
    --blue-lighter: #8CC2FF;
    --blue-pastel: #E6F2FF;
    --blue-soft: #F0F8FF;
    --blue-dark: #3A7BC8;
    
    /* 粉色系 */
    --pink-primary: #FF6B93;
    --pink-light: #FF9EBB;
    --pink-lighter: #FFC8DD;
    --pink-pastel: #FFE4EC;
    --pink-soft: #FFF0F5;
    
    /* 中性色 - 加深颜色 */
    --beige-dark: #E8E0D5;
    --beige-medium: #F0EAE1;
    --beige-light: #F5F1E9;
    --beige-cream: #FAF7F2;
    
    /* 背景 - 增加不透明度 */
    --bg-gradient: linear-gradient(rgba(232, 224, 213, 0.95), rgba(240, 234, 225, 0.98));
    
    /* 文字颜色 */
    --text-dark: #5A4B4B;
    --text-medium: #7A6B6B;
    --text-light: #9A8B8B;
    --text-white: #FFFFFF;
    
    /* 边框渐变 */
    --gradient-blue-pink: linear-gradient(135deg, var(--blue-primary) 0%, var(--pink-primary) 100%);
    --gradient-pink-blue: linear-gradient(135deg, var(--pink-primary) 0%, var(--blue-primary) 100%);
    --gradient-blue: linear-gradient(135deg, var(--blue-light) 0%, var(--blue-primary) 50%, var(--blue-dark) 100%);
    --gradient-pink: linear-gradient(135deg, var(--pink-light) 0%, var(--pink-primary) 50%, #FF4081 100%);
    
    /* 阴影 */
    --shadow-light: rgba(74, 144, 226, 0.08);
    --shadow-medium: rgba(74, 144, 226, 0.12);
    --shadow-dark: rgba(74, 144, 226, 0.16);
    --shadow-pink: rgba(255, 107, 147, 0.12);
    
    /* 背景 */
    --bg-gradient: linear-gradient(rgba(245, 240, 232, 0.9), rgba(248, 244, 239, 0.95));
}

body {
    font-family: 'MyCustomFont', 'Nunito', 'Poppins', sans-serif;
    background: linear-gradient(rgba(232, 224, 213, 0.85), rgba(240, 234, 225, 0.9)), 
                url('../package/girl.jpg') no-repeat center center fixed;
    background-size: cover;
    color: var(--text-dark);
    min-height: 100vh;
    position: relative;
    overflow-x: hidden;
}

/* 顶部装饰 */
.top-decoration {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: 200px;
    background: linear-gradient(180deg, 
        rgba(74, 144, 226, 0.12) 0%, 
        rgba(255, 107, 147, 0.08) 50%, 
        transparent 100%);
    z-index: -1;
}

.bottom-decoration {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    height: 150px;
    background: linear-gradient(0deg, 
        rgba(255, 107, 147, 0.12) 0%, 
        rgba(74, 144, 226, 0.08) 50%, 
        transparent 100%);
    z-index: -1;
}

/* 容器 */
.topic-container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 25px 20px;
    position: relative;
    z-index: 1;
}

/* 头部样式 */
.topic-header {
    background: rgba(255, 255, 255, 0.9);
    border-radius: 25px;
    padding: 30px;
    margin-bottom: 40px;
    box-shadow: 0 15px 35px var(--shadow-light);
    border: 3px solid transparent;
    position: relative;
    backdrop-filter: blur(10px);
}

.topic-header::before {
    content: '';
    position: absolute;
    top: -3px;
    left: -3px;
    right: -3px;
    bottom: -3px;
    background: var(--gradient-blue-pink);
    border-radius: 28px;
    z-index: -1;
}

.header-container {
    display: flex;
    flex-direction: column;
    gap: 25px;
}

.back-home {
    display: inline-flex;
    align-items: center;
    gap: 12px;
    color: var(--blue-primary);
    text-decoration: none;
    font-weight: 700;
    font-size: 1.1rem;
    padding: 12px 20px;
    background: rgba(255, 255, 255, 0.9);
    border-radius: 50px;
    box-shadow: 0 5px 15px var(--shadow-light);
    border: 2px solid;
    border-image: var(--gradient-blue);
    border-image-slice: 1;
    max-width: fit-content;
    transition: all 0.3s ease;
}

.back-home:hover {
    transform: translateX(-5px);
    box-shadow: 0 8px 25px var(--shadow-medium);
}

.header-content {
    text-align: center;
}

.topic-main-title {
    font-size: 2.8rem;
    color: var(--text-dark);
    margin-bottom: 20px;
    font-weight: 800;
    background: var(--gradient-blue-pink);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.topic-meta {
    display: flex;
    justify-content: center;
    gap: 20px;
    flex-wrap: wrap;
    margin-top: 20px;
}

.topic-grade, .topic-level, .topic-number {
    padding: 10px 22px;
    border-radius: 25px;
    font-weight: 700;
    font-size: 1rem;
    letter-spacing: 0.5px;
}

.grade-7-badge {
    background: var(--gradient-blue);
    color: white;
    border: 2px solid white;
}

.grade-8-badge {
    background: var(--gradient-pink);
    color: white;
    border: 2px solid white;
}

.topic-level {
    background: rgba(255, 255, 255, 0.9);
    color: var(--text-dark);
    border: 2px solid;
    border-image: var(--gradient-blue-pink);
    border-image-slice: 1;
}

.topic-number {
    background: rgba(255, 255, 255, 0.9);
    color: var(--text-dark);
    font-weight: 800;
    border: 2px solid;
    border-image: var(--gradient-blue);
    border-image-slice: 1;
}

/* 内容区域 */
.topic-content {
    display: flex;
    flex-direction: column;
    gap: 35px;
}

/* 内容区块 */
.content-section {
    background: rgba(255, 255, 255, 0.9);
    border-radius: 22px;
    padding: 35px;
    box-shadow: 0 15px 35px var(--shadow-light);
    border: 3px solid transparent;
    transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    position: relative;
    overflow: hidden;
    backdrop-filter: blur(5px);
}

.content-section::before {
    content: '';
    position: absolute;
    top: -3px;
    left: -3px;
    right: -3px;
    bottom: -3px;
    border-radius: 25px;
    z-index: -1;
    opacity: 0.7;
    transition: opacity 0.3s ease;
}

.overview-section::before {
    background: var(--gradient-blue-pink);
}

.explanation-section::before {
    background: var(--gradient-blue);
}

.code-section::before {
    background: var(--gradient-pink);
}

.tips-section::before {
    background: var(--gradient-blue-pink);
}

.practice-section::before {
    background: var(--gradient-blue);
}

.summary-section::before {
    background: var(--gradient-pink);
}

.content-section:hover {
    transform: translateY(-8px);
    box-shadow: 0 25px 50px var(--shadow-dark);
    background: white;
}

.content-section:hover::before {
    opacity: 1;
}

.content-section h2 {
    color: var(--text-dark);
    font-size: 1.9rem;
    margin-bottom: 30px;
    display: flex;
    align-items: center;
    gap: 18px;
    font-weight: 800;
}

.content-section h2 i {
    font-size: 1.7rem;
    background: var(--gradient-blue-pink);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* 概述区域 */
.overview-content {
    display: flex;
    align-items: center;
    gap: 30px;
}

.overview-icon {
    width: 90px;
    height: 90px;
    border-radius: 22px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.8rem;
    color: white;
    flex-shrink: 0;
    box-shadow: 0 12px 25px var(--shadow-medium);
    border: 3px solid white;
}

/* 根据知识点ID设置不同的渐变背景 */
[data-topic-id="1"] .overview-icon { background: var(--gradient-blue); }
[data-topic-id="2"] .overview-icon { background: var(--gradient-pink); }
[data-topic-id="3"] .overview-icon { background: var(--gradient-blue-pink); }
[data-topic-id="4"] .overview-icon { background: var(--gradient-blue); }
[data-topic-id="5"] .overview-icon { background: var(--gradient-pink); }
[data-topic-id="6"] .overview-icon { background: var(--gradient-blue-pink); }
[data-topic-id="7"] .overview-icon { background: var(--gradient-blue); }

.overview-text {
    flex-grow: 1;
}

.topic-subtitle {
    font-size: 1.5rem;
    color: var(--text-dark);
    margin-bottom: 18px;
    font-weight: 700;
    line-height: 1.4;
}

.topic-intro {
    font-size: 1.15rem;
    color: var(--text-medium);
    line-height: 1.7;
}

/* 详细讲解 */
.explanation-content h3 {
    color: var(--text-dark);
    font-size: 1.6rem;
    margin: 35px 0 20px 0;
    display: flex;
    align-items: center;
    gap: 15px;
    font-weight: 700;
}

.explanation-content h3:first-child {
    margin-top: 0;
}

.explanation-content h3 i {
    font-size: 1.4rem;
    color: var(--blue-primary);
}

.explanation-content h4 {
    color: var(--pink-primary);
    font-size: 1.3rem;
    margin: 25px 0 15px 0;
    display: flex;
    align-items: center;
    gap: 12px;
    font-weight: 700;
}

.explanation-content h4 i {
    font-size: 1.2rem;
}

.explanation-block {
    background: rgba(255, 255, 255, 0.95);
    border-radius: 18px;
    padding: 25px;
    margin: 25px 0;
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.04);
    border: 2px solid;
}

/* 交替使用蓝粉边框 */
.explanation-content .explanation-block:nth-child(odd) {
    border-image: var(--gradient-blue);
    border-image-slice: 1;
}

.explanation-content .explanation-block:nth-child(even) {
    border-image: var(--gradient-pink);
    border-image-slice: 1;
}

.explanation-block ul {
    margin-left: 25px;
    margin-bottom: 0;
}

.explanation-block li {
    margin-bottom: 12px;
    color: var(--text-medium);
    line-height: 1.7;
    font-size: 1.05rem;
}

.explanation-block code {
    background: rgba(74, 144, 226, 0.1);
    color: var(--blue-dark);
    padding: 3px 8px;
    border-radius: 6px;
    font-family: 'Courier New', monospace;
    font-weight: 700;
    font-size: 0.95rem;
    border: 1px solid rgba(74, 144, 226, 0.2);
}

.explanation-block pre {
    background: #f8f9fa;
    border-radius: 10px;
    padding: 20px;
    margin: 15px 0;
    overflow-x: auto;
    border: 2px solid #e9ecef;
}

.explanation-block pre code {
    background: none;
    border: none;
    padding: 0;
    color: #495057;
}

/* 代码区域 */
.code-container {
    background: #282c34;
    border-radius: 15px;
    overflow: hidden;
    margin-bottom: 30px;
    border: 3px solid;
    border-image: var(--gradient-blue);
    border-image-slice: 1;
}

.code-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 18px 25px;
    background: rgba(0, 0, 0, 0.4);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.code-filename {
    color: #ccc;
    font-family: 'Courier New', monospace;
    font-size: 1rem;
    font-weight: 600;
}

.copy-code-btn {
    background: var(--gradient-pink);
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1rem;
    display: flex;
    align-items: center;
    gap: 10px;
    transition: all 0.3s ease;
    font-weight: 700;
    border: 2px solid rgba(255, 255, 255, 0.2);
}

.copy-code-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 20px rgba(255, 107, 147, 0.4);
}

.code-container pre {
    margin: 0;
    padding: 25px;
    overflow-x: auto;
    max-height: 500px;
    overflow-y: auto;
}

.code-container code {
    font-family: 'Consolas', 'Monaco', 'Courier New', monospace;
    font-size: 1.05rem;
    line-height: 1.6;
}

/* 代码输出 */
.code-output {
    background: rgba(40, 44, 52, 0.95);
    border-radius: 15px;
    padding: 25px;
    border: 3px solid;
    border-image: var(--gradient-pink);
    border-image-slice: 1;
}

.code-output h4 {
    color: var(--pink-light);
    margin-bottom: 20px;
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 1.3rem;
    font-weight: 700;
}

.output-content {
    background: rgba(0, 0, 0, 0.4);
    color: #8cc265;
    padding: 20px;
    border-radius: 10px;
    font-family: 'Courier New', monospace;
    white-space: pre-wrap;
    line-height: 1.6;
    margin: 0;
    overflow-x: auto;
    font-size: 1.05rem;
}

/* 学习提示 */
.tips-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 25px;
}

.tip-card {
    background: white;
    border-radius: 18px;
    padding: 25px;
    display: flex;
    gap: 20px;
    align-items: flex-start;
    transition: all 0.3s ease;
    border: 3px solid transparent;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.05);
}

/* 交替使用蓝粉边框 */
.tips-grid .tip-card:nth-child(odd) {
    border-image: var(--gradient-blue);
    border-image-slice: 1;
}

.tips-grid .tip-card:nth-child(even) {
    border-image: var(--gradient-pink);
    border-image-slice: 1;
}

.tip-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 20px 40px var(--shadow-medium);
}

.tip-number {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: 800;
    font-size: 1.2rem;
    flex-shrink: 0;
    border: 2px solid white;
}

/* 交替使用蓝粉背景 */
.tips-grid .tip-card:nth-child(odd) .tip-number {
    background: var(--gradient-blue);
}

.tips-grid .tip-card:nth-child(even) .tip-number {
    background: var(--gradient-pink);
}

.tip-content p {
    margin: 0;
    color: var(--text-medium);
    line-height: 1.7;
    font-size: 1.05rem;
}

/* 练习题 */
.practice-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 30px;
}

.exercise-card {
    background: white;
    border-radius: 18px;
    padding: 30px;
    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.06);
    border: 3px solid transparent;
    transition: all 0.3s ease;
}

/* 交替使用蓝粉边框 */
.practice-grid .exercise-card:nth-child(odd) {
    border-image: var(--gradient-blue);
    border-image-slice: 1;
}

.practice-grid .exercise-card:nth-child(even) {
    border-image: var(--gradient-pink);
    border-image-slice: 1;
}

.exercise-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 25px 45px var(--shadow-medium);
}

.exercise-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    padding-bottom: 20px;
    border-bottom: 2px solid rgba(74, 144, 226, 0.1);
}

.exercise-number {
    font-weight: 800;
    color: var(--text-dark);
    font-size: 1.2rem;
}

.difficulty {
    padding: 6px 15px;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 800;
    letter-spacing: 0.5px;
    border: 2px solid;
}

.difficulty.easy {
    background: rgba(74, 144, 226, 0.1);
    color: var(--blue-primary);
    border-color: rgba(74, 144, 226, 0.3);
}

.difficulty.medium {
    background: rgba(255, 193, 7, 0.1);
    color: #ff9800;
    border-color: rgba(255, 193, 7, 0.3);
}

.difficulty.hard {
    background: rgba(255, 107, 147, 0.1);
    color: var(--pink-primary);
    border-color: rgba(255, 107, 147, 0.3);
}

.exercise-content p {
    color: var(--text-dark);
    line-height: 1.7;
    margin-bottom: 25px;
    font-size: 1.1rem;
}

.exercise-hint {
    margin-top: 20px;
}

.hint-btn {
    background: rgba(255, 255, 255, 0.9);
    color: var(--blue-primary);
    border: 2px solid;
    border-image: var(--gradient-blue);
    border-image-slice: 1;
    padding: 10px 20px;
    border-radius: 25px;
    cursor: pointer;
    font-size: 1rem;
    display: flex;
    align-items: center;
    gap: 10px;
    transition: all 0.3s ease;
    font-weight: 700;
}

.practice-grid .exercise-card:nth-child(even) .hint-btn {
    border-image: var(--gradient-pink);
    color: var(--pink-primary);
}

.hint-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 20px var(--shadow-light);
}

.hint-content {
    display: none;
    margin-top: 20px;
    padding: 20px;
    background: rgba(255, 255, 255, 0.95);
    border-radius: 15px;
    border: 2px solid;
    border-image: var(--gradient-blue-pink);
    border-image-slice: 1;
}

.hint-content p {
    margin: 0;
    color: var(--text-medium);
    line-height: 1.7;
    font-size: 1.05rem;
}

/* 知识点总结 */
.summary-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 35px;
}

.summary-points h3, .summary-next h3 {
    color: var(--text-dark);
    margin-bottom: 20px;
    font-size: 1.4rem;
    font-weight: 800;
    display: flex;
    align-items: center;
    gap: 12px;
}

.summary-points h3 i, .summary-next h3 i {
    color: var(--blue-primary);
}

.summary-points ul {
    list-style: none;
    padding: 0;
}

.summary-points li {
    margin-bottom: 15px;
    color: var(--text-medium);
    display: flex;
    align-items: center;
    gap: 15px;
    font-size: 1.1rem;
    line-height: 1.6;
}

.summary-points li i {
    color: var(--pink-primary);
    font-size: 1.1rem;
}

.summary-next p {
    color: var(--text-medium);
    line-height: 1.7;
    margin-bottom: 25px;
    font-size: 1.1rem;
}

.next-preview-btn {
    display: inline-flex;
    align-items: center;
    gap: 12px;
    background: var(--gradient-blue-pink);
    color: white;
    padding: 12px 25px;
    border-radius: 25px;
    text-decoration: none;
    font-weight: 800;
    transition: all 0.3s ease;
    border: 2px solid white;
}

.next-preview-btn:hover {
    transform: translateX(8px);
    box-shadow: 0 12px 25px rgba(74, 144, 226, 0.3);
}

/* 导航按钮 */
.navigation-buttons {
    display: flex;
    justify-content: space-between;
    margin: 50px 0 30px;
    gap: 25px;
}

.nav-btn {
    padding: 18px 30px;
    border-radius: 15px;
    text-decoration: none;
    font-weight: 800;
    display: flex;
    align-items: center;
    gap: 15px;
    transition: all 0.3s ease;
    min-width: 200px;
    justify-content: center;
    border: 3px solid transparent;
}

.prev-btn {
    background: white;
    color: var(--blue-primary);
    border-image: var(--gradient-blue);
    border-image-slice: 1;
}

.prev-btn:hover {
    background: var(--blue-pastel);
    transform: translateX(-8px);
    box-shadow: 0 15px 30px var(--shadow-medium);
}

.home-btn {
    background: white;
    color: var(--text-dark);
    border-image: var(--gradient-blue-pink);
    border-image-slice: 1;
}

.home-btn:hover {
    background: var(--pink-pastel);
    transform: translateY(-5px);
    box-shadow: 0 15px 30px var(--shadow-pink);
}

.next-btn {
    background: white;
    color: var(--pink-primary);
    border-image: var(--gradient-pink);
    border-image-slice: 1;
}

.next-btn:hover {
    background: var(--pink-pastel);
    transform: translateX(8px);
    box-shadow: 0 15px 30px var(--shadow-pink);
}

.nav-btn-placeholder {
    visibility: hidden;
}

/* 页脚样式 */
.topic-footer {
    margin-top: 60px;
    padding: 35px;
    text-align: center;
    background: rgba(255, 255, 255, 0.9);
    border-radius: 25px;
    box-shadow: 0 15px 35px var(--shadow-light);
    border: 3px solid transparent;
    position: relative;
    backdrop-filter: blur(10px);
}

.topic-footer::before {
    content: '';
    position: absolute;
    top: -3px;
    left: -3px;
    right: -3px;
    bottom: -3px;
    background: var(--gradient-blue-pink);
    border-radius: 28px;
    z-index: -1;
}

.footer-content {
    max-width: 800px;
    margin: 0 auto;
}

.footer-logo {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 15px;
    font-size: 1.5rem;
    color: var(--text-dark);
    margin-bottom: 20px;
    font-weight: 800;
    background: var(--gradient-blue-pink);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.footer-logo i {
    font-size: 1.7rem;
}

.footer-copyright {
    color: var(--text-medium);
    margin-bottom: 12px;
    font-size: 1.05rem;
}

.footer-note {
    color: var(--text-medium);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    font-size: 1.05rem;
    flex-wrap: wrap;
}

.footer-note i {
    color: var(--blue-primary);
}

/* 返回顶部按钮 */
.back-to-top {
    position: fixed;
    bottom: 40px;
    right: 40px;
    width: 60px;
    height: 60px;
    background: var(--gradient-blue-pink);
    color: white;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    font-size: 1.4rem;
    z-index: 1000;
    display: none;
    transition: all 0.3s ease;
    box-shadow: 0 8px 25px rgba(74, 144, 226, 0.3);
    border: 3px solid white;
}

.back-to-top:hover {
    transform: translateY(-5px) scale(1.1);
    box-shadow: 0 15px 35px rgba(74, 144, 226, 0.4);
}

/* 响应式设计 */
@media (max-width: 1024px) {
    .tips-grid, .practice-grid, .summary-content {
        grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    }
}

@media (max-width: 768px) {
    .topic-container {
        padding: 20px 15px;
    }
    
    .topic-header {
        padding: 25px 20px;
    }
    
    .topic-main-title {
        font-size: 2.2rem;
    }
    
    .topic-meta {
        gap: 15px;
    }
    
    .topic-grade, .topic-level, .topic-number {
        padding: 8px 18px;
        font-size: 0.95rem;
    }
    
    .content-section {
        padding: 25px 20px;
    }
    
    .content-section h2 {
        font-size: 1.6rem;
    }
    
    .overview-content {
        flex-direction: column;
        text-align: center;
        gap: 20px;
    }
    
    .overview-icon {
        width: 80px;
        height: 80px;
        font-size: 2.5rem;
    }
    
    .topic-subtitle {
        font-size: 1.3rem;
    }
    
    .tips-grid, .practice-grid, .summary-content {
        grid-template-columns: 1fr;
    }
    
    .navigation-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .nav-btn {
        width: 100%;
        max-width: 350px;
    }
    
    .nav-btn-placeholder {
        display: none;
    }
    
    .code-container pre {
        padding: 20px 15px;
        font-size: 0.95rem;
    }
    
    .back-home {
        align-self: center;
    }
}

@media (max-width: 480px) {
    .topic-main-title {
        font-size: 1.9rem;
    }
    
    .topic-subtitle {
        font-size: 1.2rem;
    }
    
    .overview-icon {
        width: 70px;
        height: 70px;
        font-size: 2.2rem;
    }
    
    .content-section h2 {
        font-size: 1.4rem;
        flex-direction: column;
        align-items: flex-start;
        gap: 10px;
    }
    
    .exercise-card {
        padding: 25px 20px;
    }
    
    .back-to-top {
        bottom: 25px;
        right: 25px;
        width: 50px;
        height: 50px;
        font-size: 1.2rem;
    }
}

/* 打印样式 */
@media print {
    .top-decoration,
    .bottom-decoration,
    .back-to-top,
    .copy-code-btn,
    .hint-btn,
    .next-preview-btn,
    .nav-btn {
        display: none;
    }
    
    .content-section {
        box-shadow: none;
        border: 1px solid #ddd;
        page-break-inside: avoid;
    }
    
    body {
        background: white !important;
    }
    
    .topic-header,
    .topic-footer {
        box-shadow: none;
        border: 1px solid #ddd;
    }
}