/* =====================================================
   还差几颗详细玩法 - 样式表
   设计理念：拼图蓝+神秘紫，解谜感，成就感
   ===================================================== */

/* CSS 变量 */
:root {
    /* 主色调 - 拼图蓝 */
    --primary: #42A5F5;
    --primary-light: #64B5F6;
    --primary-dark: #1E88E5;

    /* 神秘紫 */
    --purple: #7E57C2;
    --purple-light: #9575CD;
    --purple-dark: #5E35B1;

    /* 成功/正确 - 绿色 */
    --positive: #66BB6A;
    --positive-light: #81C784;

    /* 错误/警示 - 橙红色 */
    --negative: #FF7043;
    --negative-light: #FFAB91;

    /* 新增块 - 金色 */
    --gold: #FFD54F;
    --gold-light: #FFECB3;

    /* 中性色 */
    --bg: #F8FAFF;
    --bg-warm: #EEF3FF;
    --bg-section: #F5F8FF;
    --text: #1A237E;
    --text-light: #3949AB;
    --text-muted: #7986CB;
    --border: #C5CAE9;

    /* 间距 */
    --space-xs: 0.5rem;
    --space-sm: 1rem;
    --space-md: 1.5rem;
    --space-lg: 2.5rem;
    --space-xl: 4rem;
    --space-2xl: 6rem;

    /* 圆角 */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --radius-xl: 32px;

    /* 阴影 */
    --shadow-sm: 0 2px 8px rgba(66, 165, 245, 0.1);
    --shadow-md: 0 4px 20px rgba(66, 165, 245, 0.12);
    --shadow-lg: 0 8px 40px rgba(66, 165, 245, 0.15);
    --shadow-purple: 0 4px 20px rgba(126, 87, 194, 0.2);

    /* 过渡 */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
}

/* 基础重置 */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.7;
    overflow-x: hidden;
}

/* 容器 */
.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 0 var(--space-md);
}

/* =====================================================
   导航栏
   ===================================================== */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(248, 250, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border);
    z-index: 1000;
    padding: var(--space-sm) 0;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--space-md);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-brand {
    font-family: 'Noto Serif SC', serif;
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--primary);
    text-decoration: none;
}

.nav-links {
    display: flex;
    gap: var(--space-md);
}

.nav-links a {
    color: var(--text-light);
    text-decoration: none;
    font-size: 0.9rem;
    transition: color var(--transition-fast);
}

.nav-links a:hover {
    color: var(--primary);
}

/* =====================================================
   进度条
   ===================================================== */
.progress-bar {
    position: fixed;
    top: 57px;
    left: 0;
    right: 0;
    height: 3px;
    background: var(--border);
    z-index: 999;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary), var(--purple));
    width: 0%;
    transition: width 0.1s ease-out;
}

/* =====================================================
   章节导航点
   ===================================================== */
.chapter-nav {
    position: fixed;
    right: 30px;
    top: 50%;
    transform: translateY(-50%);
    display: flex;
    flex-direction: column;
    gap: 12px;
    z-index: 100;
}

.chapter-dot {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: var(--border);
    cursor: pointer;
    transition: all var(--transition-normal);
    position: relative;
}

.chapter-dot:hover {
    background: var(--primary-light);
    transform: scale(1.2);
}

.chapter-dot.active {
    background: var(--primary);
    box-shadow: 0 0 0 4px rgba(66, 165, 245, 0.2);
}

.chapter-dot::before {
    content: attr(title);
    position: absolute;
    right: 24px;
    top: 50%;
    transform: translateY(-50%);
    background: var(--text);
    color: white;
    padding: 4px 12px;
    border-radius: 6px;
    font-size: 12px;
    white-space: nowrap;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-fast);
}

.chapter-dot:hover::before {
    opacity: 1;
    visibility: visible;
}

/* =====================================================
   Hero区
   ===================================================== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 120px 24px 80px;
    background: linear-gradient(180deg, var(--bg) 0%, var(--bg-warm) 100%);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -20%;
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(66, 165, 245, 0.08) 0%, transparent 70%);
    pointer-events: none;
}

.hero::after {
    content: '';
    position: absolute;
    bottom: -30%;
    left: -10%;
    width: 400px;
    height: 400px;
    background: radial-gradient(circle, rgba(126, 87, 194, 0.06) 0%, transparent 70%);
    pointer-events: none;
}

.hero-content {
    text-align: center;
    max-width: 700px;
    position: relative;
    z-index: 1;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: linear-gradient(135deg, var(--primary), var(--purple));
    color: white;
    padding: 8px 20px;
    border-radius: 50px;
    font-size: 0.9rem;
    font-weight: 500;
    margin-bottom: var(--space-md);
    box-shadow: var(--shadow-md);
}

.badge-icon {
    width: 18px;
    height: 18px;
}

.hero-title {
    margin-bottom: var(--space-md);
}

.title-line {
    display: block;
    font-family: 'Noto Serif SC', serif;
    font-size: 3.5rem;
    font-weight: 700;
    color: var(--text);
    margin-bottom: 8px;
}

.title-highlight {
    display: block;
    font-size: 1.5rem;
    font-weight: 400;
    color: var(--purple);
}

.hero-subtitle {
    font-size: 1.2rem;
    color: var(--text-light);
    margin-bottom: var(--space-lg);
    line-height: 1.8;
}

.hero-subtitle strong {
    color: var(--primary);
}

.meta-info {
    display: flex;
    justify-content: center;
    gap: var(--space-lg);
    margin-bottom: var(--space-xl);
    flex-wrap: wrap;
}

.meta-item {
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--text-muted);
    font-size: 0.95rem;
}

.meta-item svg {
    width: 20px;
    height: 20px;
    color: var(--primary);
}

.hero-cta {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 12px;
}

.scroll-hint {
    color: var(--text-muted);
    font-size: 0.9rem;
}

.scroll-arrow {
    animation: bounce 2s infinite;
}

.scroll-arrow svg {
    width: 24px;
    height: 24px;
    color: var(--primary);
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% { transform: translateY(0); }
    40% { transform: translateY(-10px); }
    60% { transform: translateY(-5px); }
}

/* =====================================================
   通用Section样式
   ===================================================== */
.section {
    padding: var(--space-2xl) 0;
}

.section-header {
    text-align: center;
    margin-bottom: var(--space-xl);
}

.section-number {
    display: inline-block;
    background: linear-gradient(135deg, var(--primary), var(--purple));
    color: white;
    padding: 6px 16px;
    border-radius: 50px;
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: var(--space-sm);
}

.section-title {
    font-family: 'Noto Serif SC', serif;
    font-size: 2rem;
    color: var(--text);
    margin-bottom: 8px;
}

.section-desc {
    color: var(--text-muted);
    font-size: 1rem;
}

/* =====================================================
   效果对比区
   ===================================================== */
.section-contrast {
    background: var(--bg-warm);
}

.contrast-container {
    display: flex;
    align-items: stretch;
    gap: var(--space-md);
    margin-bottom: var(--space-lg);
}

.contrast-card {
    flex: 1;
    background: white;
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
}

.contrast-header {
    padding: var(--space-md);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.before .contrast-header {
    background: linear-gradient(135deg, #ffebee, #fce4ec);
}

.after .contrast-header {
    background: linear-gradient(135deg, #e8f5e9, #f1f8e9);
}

.contrast-label {
    font-weight: 600;
    font-size: 1.1rem;
}

.before .contrast-label { color: #c62828; }
.after .contrast-label { color: #2e7d32; }

.contrast-icon {
    font-size: 1.5rem;
}

.contrast-content {
    padding: var(--space-md);
}

.contrast-content ul {
    list-style: none;
}

.contrast-content li {
    padding: 8px 0;
    padding-left: 28px;
    position: relative;
    color: var(--text-light);
}

.before .contrast-content li::before {
    content: '✗';
    position: absolute;
    left: 0;
    color: #ef5350;
    font-weight: bold;
}

.after .contrast-content li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: #66bb6a;
    font-weight: bold;
}

.contrast-arrow {
    display: flex;
    align-items: center;
    padding: 0 var(--space-sm);
}

.contrast-arrow svg {
    width: 32px;
    height: 32px;
    color: var(--primary);
}

.why-important {
    display: flex;
    gap: var(--space-md);
    background: white;
    padding: var(--space-lg);
    border-radius: var(--radius-lg);
    border-left: 4px solid var(--purple);
    box-shadow: var(--shadow-sm);
}

.why-icon {
    flex-shrink: 0;
    width: 48px;
    height: 48px;
    background: linear-gradient(135deg, var(--primary), var(--purple));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
}

.why-icon svg {
    width: 24px;
    height: 24px;
    color: white;
}

.why-content {
    flex: 1;
}

.why-title {
    font-weight: 600;
    color: var(--purple);
    margin-bottom: 8px;
}

.why-content p:last-child {
    color: var(--text-light);
    line-height: 1.8;
}

/* =====================================================
   材料准备区
   ===================================================== */
.materials-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: var(--space-md);
    margin-bottom: var(--space-lg);
}

.material-item {
    background: white;
    padding: var(--space-md);
    border-radius: var(--radius-md);
    text-align: center;
    box-shadow: var(--shadow-sm);
    position: relative;
    transition: transform var(--transition-normal);
}

.material-item:hover {
    transform: translateY(-4px);
}

.material-icon {
    font-size: 2.5rem;
    margin-bottom: 8px;
}

.material-name {
    display: block;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 4px;
}

.material-tag {
    display: inline-block;
    padding: 2px 10px;
    border-radius: 50px;
    font-size: 0.75rem;
    font-weight: 500;
}

.required .material-tag {
    background: var(--primary-light);
    color: white;
}

.optional .material-tag {
    background: var(--gold-light);
    color: #f57c00;
}

.material-note {
    display: block;
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-top: 8px;
}

.materials-tip {
    background: linear-gradient(135deg, var(--bg-warm), #fff);
    padding: var(--space-md);
    border-radius: var(--radius-md);
    border-left: 4px solid var(--primary);
    margin-bottom: var(--space-lg);
}

.materials-tip strong {
    color: var(--primary);
}

/* 角色介绍 */
.roles-intro {
    background: white;
    padding: var(--space-lg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
}

.subsection-title {
    font-family: 'Noto Serif SC', serif;
    font-size: 1.3rem;
    color: var(--text);
    margin-bottom: var(--space-md);
    text-align: center;
}

.roles-container {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-lg);
    flex-wrap: wrap;
}

.role-card {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    padding: var(--space-md);
    border-radius: var(--radius-md);
    min-width: 200px;
}

.mom-role {
    background: linear-gradient(135deg, #e3f2fd, #bbdefb);
}

.kid-role {
    background: linear-gradient(135deg, #ede7f6, #d1c4e9);
}

.role-avatar {
    width: 60px;
    height: 60px;
    border-radius: 50%;
    background: white;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.8rem;
    box-shadow: var(--shadow-sm);
}

.kid-role .role-avatar {
    background: linear-gradient(135deg, var(--purple), var(--primary));
}

.kid-role .role-avatar svg {
    width: 32px;
    height: 32px;
    color: white;
}

.role-info h4 {
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-bottom: 2px;
}

.role-name {
    font-weight: 700;
    font-size: 1.1rem;
    color: var(--text);
    margin-bottom: 4px;
}

.role-desc {
    font-size: 0.85rem;
    color: var(--text-light);
    line-height: 1.5;
}

.role-arrow {
    font-size: 2rem;
    color: var(--primary);
}

/* =====================================================
   对话脚本区
   ===================================================== */
.section-script {
    background: var(--bg-warm);
}

/* 开场选择 */
.opening-section {
    margin-bottom: var(--space-xl);
}

.opening-tabs {
    display: flex;
    justify-content: center;
    gap: 8px;
    margin-bottom: var(--space-md);
    flex-wrap: wrap;
}

.opening-tab {
    padding: 10px 20px;
    border: 2px solid var(--border);
    background: white;
    border-radius: 50px;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-light);
    transition: all var(--transition-fast);
}

.opening-tab:hover {
    border-color: var(--primary);
    color: var(--primary);
}

.opening-tab.active {
    background: linear-gradient(135deg, var(--primary), var(--purple));
    border-color: transparent;
    color: white;
}

.opening-content {
    display: none;
    background: white;
    padding: var(--space-lg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
}

.opening-content.active {
    display: block;
}

/* 对话框 */
.dialogue-box {
    margin-bottom: var(--space-md);
}

.dialogue {
    display: flex;
    gap: var(--space-sm);
    margin-bottom: var(--space-sm);
}

.dialogue.mom {
    flex-direction: row-reverse;
}

.speaker {
    font-size: 0.8rem;
    font-weight: 600;
    margin-bottom: 4px;
}

.mom .speaker {
    color: var(--primary);
    text-align: right;
}

.child .speaker {
    color: var(--purple);
}

.bubble {
    max-width: 85%;
    padding: var(--space-sm) var(--space-md);
    border-radius: var(--radius-md);
    line-height: 1.7;
    position: relative;
}

.mom .bubble {
    background: linear-gradient(135deg, #e3f2fd, #bbdefb);
    border-bottom-right-radius: 4px;
}

.child .bubble {
    background: linear-gradient(135deg, #ede7f6, #d1c4e9);
    border-bottom-left-radius: 4px;
}

.bubble.error {
    background: linear-gradient(135deg, #ffebee, #ffcdd2);
}

.bubble.success {
    background: linear-gradient(135deg, #e8f5e9, #c8e6c9);
}

.bubble .wrong {
    color: #c62828;
    font-weight: 700;
    text-decoration: line-through;
}

.bubble .highlight {
    color: var(--primary);
    font-weight: 600;
}

.face-note {
    display: block;
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-top: 8px;
    font-style: italic;
}

/* 步骤 */
.steps-section {
    margin-bottom: var(--space-xl);
}

.script-step {
    background: white;
    border-radius: var(--radius-lg);
    margin-bottom: var(--space-md);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
}

.script-step.highlight-step {
    border-left: 4px solid var(--primary);
}

.script-step.highlight-step.learn {
    border-left-color: var(--purple);
}

.step-header {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    padding: var(--space-md);
    background: var(--bg-section);
}

.step-number {
    width: 36px;
    height: 36px;
    background: linear-gradient(135deg, var(--primary), var(--purple));
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 1.1rem;
}

.step-header h4 {
    flex: 1;
    font-size: 1.1rem;
    color: var(--text);
}

.step-tag {
    padding: 4px 12px;
    border-radius: 50px;
    font-size: 0.75rem;
    font-weight: 600;
}

.step-tag.key {
    background: var(--primary-light);
    color: white;
}

.step-tag.learn {
    background: var(--purple-light);
    color: white;
}

.step-content {
    padding: var(--space-lg);
}

/* 动作说明 */
.action-note {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: var(--space-sm) var(--space-md);
    background: var(--bg-warm);
    border-radius: var(--radius-sm);
    margin-bottom: var(--space-md);
    color: var(--text-light);
    font-size: 0.95rem;
}

.action-note svg {
    width: 20px;
    height: 20px;
    color: var(--primary);
    flex-shrink: 0;
}

.action-note.warning {
    background: #fff3e0;
}

.action-note.warning svg {
    color: #ff9800;
}

/* 拼图视觉演示 */
.visual-demo {
    background: var(--bg-section);
    padding: var(--space-lg);
    border-radius: var(--radius-md);
    margin: var(--space-md) 0;
    text-align: center;
}

.visual-demo.success {
    background: linear-gradient(135deg, #e8f5e9, #f1f8e9);
}

.puzzle-frame {
    display: flex;
    justify-content: center;
    gap: 8px;
    margin-bottom: var(--space-sm);
}

.puzzle-piece {
    width: 50px;
    height: 50px;
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 1.2rem;
}

.puzzle-piece.filled {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: white;
}

.puzzle-piece.empty {
    background: white;
    border: 3px dashed var(--border);
    color: var(--text-muted);
}

.puzzle-piece.new {
    background: linear-gradient(135deg, var(--gold), #ffc107);
    color: #5d4037;
    animation: popIn 0.3s ease;
}

@keyframes popIn {
    0% { transform: scale(0); }
    70% { transform: scale(1.1); }
    100% { transform: scale(1); }
}

.puzzle-label {
    color: var(--text-light);
    font-size: 0.95rem;
}

/* 分支Tab */
.branch-tabs {
    display: flex;
    gap: 8px;
    margin-bottom: var(--space-md);
}

.branch-tab {
    flex: 1;
    padding: 10px;
    border: 2px solid var(--border);
    background: white;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-light);
    transition: all var(--transition-fast);
}

.branch-tab:hover {
    border-color: var(--primary);
}

.branch-tab.active {
    background: var(--primary);
    border-color: var(--primary);
    color: white;
}

.branch-content {
    display: none;
}

.branch-content.active {
    display: block;
}

/* 提示框 */
.tip-box {
    padding: var(--space-md);
    border-radius: var(--radius-md);
    margin: var(--space-md) 0;
    background: #fff8e1;
    border-left: 4px solid #ffc107;
}

.tip-box.green {
    background: #e8f5e9;
    border-left-color: var(--positive);
}

.tip-box.warning {
    background: #fff3e0;
    border-left-color: #ff9800;
}

.tip-box strong {
    color: var(--text);
}

.tip-box p {
    color: var(--text-light);
    margin-top: 8px;
}

/* 对比演示 */
.compare-demo {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    background: white;
    padding: var(--space-md);
    border-radius: var(--radius-md);
    margin: var(--space-md) 0;
}

.compare-item {
    flex: 1;
    text-align: center;
    padding: var(--space-md);
    background: var(--bg-section);
    border-radius: var(--radius-sm);
}

.compare-title {
    font-weight: 700;
    color: var(--text);
    margin-bottom: 8px;
}

.compare-visual {
    font-size: 0.9rem;
    color: var(--primary);
    margin-bottom: 8px;
}

.compare-desc {
    font-size: 0.85rem;
    color: var(--text-muted);
}

.compare-vs {
    font-weight: 700;
    color: var(--purple);
    font-size: 1.2rem;
}

/* 学习要点 */
.learning-point {
    display: flex;
    gap: var(--space-md);
    background: linear-gradient(135deg, #ede7f6, #e8eaf6);
    padding: var(--space-md);
    border-radius: var(--radius-md);
    margin-top: var(--space-md);
}

.learning-icon {
    width: 40px;
    height: 40px;
    background: var(--purple);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.learning-icon svg {
    width: 20px;
    height: 20px;
    color: white;
}

.learning-text strong {
    display: block;
    color: var(--purple);
    margin-bottom: 4px;
}

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

/* 探索区 */
.explore-section {
    background: var(--bg-section);
    padding: var(--space-lg);
    border-radius: var(--radius-md);
    margin: var(--space-md) 0;
}

.explore-section h5 {
    color: var(--text);
    margin-bottom: var(--space-md);
}

.explore-options {
    display: flex;
    gap: var(--space-sm);
    flex-wrap: wrap;
}

.explore-options.vertical {
    flex-direction: column;
}

.explore-item {
    padding: var(--space-md);
    border-radius: var(--radius-sm);
    background: white;
    display: flex;
    align-items: center;
    gap: var(--space-md);
}

.puzzle-challenge {
    border-left: 4px solid var(--primary);
}

.challenge-setup {
    font-weight: 600;
    color: var(--text);
    min-width: 150px;
}

.challenge-question {
    color: var(--text-muted);
}

.challenge-answer {
    color: var(--positive);
    font-weight: 700;
}

/* 收尾 */
.ending-section {
    background: white;
    padding: var(--space-lg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
}

.ending-tips {
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
}

.ending-tip {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    padding: var(--space-sm);
    background: var(--bg-section);
    border-radius: var(--radius-sm);
}

.ending-tip .tip-icon {
    font-size: 1.5rem;
}

/* =====================================================
   锦囊区
   ===================================================== */
.section-tips {
    background: linear-gradient(180deg, var(--bg) 0%, var(--bg-warm) 100%);
}

.tips-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--space-md);
}

.tip-card {
    background: white;
    padding: var(--space-lg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    position: relative;
    overflow: hidden;
}

.tip-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary), var(--purple));
}

.tip-number {
    width: 32px;
    height: 32px;
    background: var(--primary);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    margin-bottom: var(--space-sm);
}

.tip-card h4 {
    font-size: 1.1rem;
    color: var(--text);
    margin-bottom: 8px;
}

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

.tip-example {
    background: var(--bg-section);
    padding: var(--space-sm);
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
}

.example-label {
    color: var(--text-muted);
    font-size: 0.8rem;
}

/* =====================================================
   常见问题区
   ===================================================== */
.section-problems {
    background: var(--bg-warm);
}

.problems-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--space-md);
}

.problem-flip-card {
    height: 280px;
    perspective: 1000px;
    cursor: pointer;
}

.problem-flip-card .flip-front,
.problem-flip-card .flip-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    border-radius: var(--radius-lg);
    padding: var(--space-lg);
    transition: transform 0.6s;
}

.flip-front {
    background: white;
    box-shadow: var(--shadow-sm);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
}

.flip-icon {
    font-size: 3rem;
    margin-bottom: var(--space-sm);
}

.flip-front h3 {
    font-size: 1.2rem;
    color: var(--text);
    margin-bottom: 8px;
}

.flip-hint {
    color: var(--text-muted);
    font-size: 0.85rem;
}

.flip-back {
    background: linear-gradient(135deg, var(--primary), var(--purple));
    color: white;
    transform: rotateY(180deg);
    overflow-y: auto;
}

.flip-back h3 {
    font-size: 1.1rem;
    margin-bottom: var(--space-md);
    padding-bottom: var(--space-sm);
    border-bottom: 1px solid rgba(255,255,255,0.3);
}

.solution p {
    margin-bottom: 8px;
    font-size: 0.9rem;
}

.solution .symptom strong,
.solution .action strong {
    opacity: 0.8;
}

.speech-example {
    background: rgba(255,255,255,0.15);
    padding: var(--space-sm);
    border-radius: var(--radius-sm);
    margin-top: var(--space-sm);
    font-size: 0.85rem;
}

.speech-example .label {
    opacity: 0.7;
    display: block;
    margin-bottom: 4px;
}

.problem-flip-card.flipped .flip-front {
    transform: rotateY(-180deg);
}

.problem-flip-card.flipped .flip-back {
    transform: rotateY(0);
}

/* =====================================================
   进阶玩法区
   ===================================================== */
.section-advanced {
    background: var(--bg);
}

.difficulty-ladder {
    display: flex;
    flex-direction: column;
    max-width: 500px;
    margin: 0 auto var(--space-xl);
}

.ladder-item {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    padding: var(--space-md);
    background: white;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
    position: relative;
}

.ladder-item.current {
    border: 2px solid var(--primary);
    background: var(--bg-warm);
}

.ladder-level {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, var(--primary), var(--purple));
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 0.85rem;
    flex-shrink: 0;
}

.ladder-content {
    flex: 1;
}

.ladder-content h4 {
    font-size: 1rem;
    color: var(--text);
    margin-bottom: 4px;
}

.ladder-content p {
    font-size: 0.9rem;
    color: var(--text-muted);
}

.ladder-badge {
    position: absolute;
    top: -8px;
    right: -8px;
    background: var(--primary);
    color: white;
    padding: 4px 12px;
    border-radius: 50px;
    font-size: 0.75rem;
    font-weight: 600;
}

.ladder-connector {
    width: 4px;
    height: 20px;
    background: var(--border);
    margin-left: 38px;
}

/* 相关玩法 */
.related-plays {
    margin-bottom: var(--space-xl);
}

.related-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--space-md);
}

.related-card {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    padding: var(--space-md);
    background: white;
    border-radius: var(--radius-md);
    text-decoration: none;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-normal);
}

.related-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
}

.related-icon {
    font-size: 2rem;
}

.related-info h4 {
    font-size: 1rem;
    color: var(--text);
    margin-bottom: 4px;
}

.related-info p {
    font-size: 0.85rem;
    color: var(--text-muted);
}

/* 总结卡片 */
.summary-card {
    background: white;
    padding: var(--space-lg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    margin-bottom: var(--space-lg);
}

.summary-card h3 {
    font-family: 'Noto Serif SC', serif;
    font-size: 1.2rem;
    color: var(--text);
    margin-bottom: var(--space-md);
    text-align: center;
}

.summary-content {
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
}

.summary-item {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    padding: var(--space-sm);
    background: var(--bg-section);
    border-radius: var(--radius-sm);
}

.summary-item.success .summary-icon {
    color: var(--positive);
    font-weight: 700;
}

/* 最终信息 */
.final-message {
    text-align: center;
    padding: var(--space-xl);
    background: linear-gradient(135deg, var(--bg-warm), #fff);
    border-radius: var(--radius-xl);
}

.message-lead {
    color: var(--text-muted);
    font-size: 1rem;
    margin-bottom: var(--space-sm);
}

.message-main {
    font-family: 'Noto Serif SC', serif;
    font-size: 1.5rem;
    color: var(--text);
    line-height: 1.8;
}

.highlight-word {
    color: var(--primary);
    font-weight: 700;
}

/* =====================================================
   页脚
   ===================================================== */
.footer {
    background: var(--text);
    color: white;
    padding: var(--space-xl) 0;
    text-align: center;
}

.footer p {
    margin-bottom: var(--space-md);
    opacity: 0.8;
}

.footer-links {
    display: flex;
    justify-content: center;
    gap: var(--space-lg);
}

.footer-links a {
    color: white;
    text-decoration: none;
    opacity: 0.7;
    transition: opacity var(--transition-fast);
}

.footer-links a:hover {
    opacity: 1;
}

/* =====================================================
   响应式设计
   ===================================================== */
@media (max-width: 768px) {
    .chapter-nav {
        display: none;
    }

    .title-line {
        font-size: 2.5rem;
    }

    .title-highlight {
        font-size: 1.2rem;
    }

    .contrast-container {
        flex-direction: column;
    }

    .contrast-arrow {
        transform: rotate(90deg);
        padding: var(--space-sm) 0;
    }

    .roles-container {
        flex-direction: column;
    }

    .role-arrow {
        transform: rotate(90deg);
    }

    .compare-demo {
        flex-direction: column;
    }

    .compare-vs {
        padding: var(--space-sm) 0;
    }

    .branch-tabs {
        flex-direction: column;
    }

    .explore-item {
        flex-direction: column;
        text-align: center;
        gap: var(--space-sm);
    }

    .challenge-setup {
        min-width: auto;
    }
}

@media (max-width: 480px) {
    html {
        font-size: 14px;
    }

    .opening-tabs {
        flex-direction: column;
    }

    .opening-tab {
        width: 100%;
    }

    .puzzle-piece {
        width: 40px;
        height: 40px;
        font-size: 1rem;
    }

    .meta-info {
        flex-direction: column;
        gap: var(--space-sm);
    }
}