/**
 * SSG 教程详情页样式 - Tutorial Overview
 *
 * 参照 https://www.codefather.cn/course/1803988290715377665 设计
 * 配色：暖黄温馨风 #FA8C16（学习/阅读场景，温暖舒适）
 *
 * 布局：全屏三栏（左目录 260px | 中内容 flex-1 | 右大纲/推荐 260px）
 * 模式：首页模式（Banner+Tab+介绍/目录，右侧推荐） / 文章模式（文章内容，右侧大纲）
 *
 * 依赖：auth.css（--primary-color 变量）
 * 引入：SharedSnippet.cssTags()
 */

/* ========== Design Tokens ========== */
:root {
    /* 主色调 - 暖黄温馨风 */
    --to-primary: #FA8C16;
    --to-primary-hover: #D46B08;
    --to-primary-light: #FFF7E6;
    --to-primary-border: #FFE7BA;

    /* 中性色 - 暖白背景 */
    --to-text-main: #1D2129;
    --to-text-secondary: #4E5969;
    --to-text-muted: #86909C;
    --to-text-placeholder: #C9CDD4;
    --to-border: #FFE7BA;
    --to-bg-page: #FFFBF3;
    --to-bg-card: #FFFFFF;
    --to-bg-hover: #FFF7E6;

    /* 付费色（改为暖黄渐变） */
    --to-paid-gradient: linear-gradient(135deg, #FA8C16 0%, #D46B08 100%);
    --to-paid-border: #D46B08;

    /* 圆角 */
    --to-radius-card: 12px;
    --to-radius-button: 8px;
    --to-radius-tag: 4px;
    --to-radius-input: 20px;

    /* 间距 */
    --to-spacing-page: 20px;
    --to-spacing-card: 16px;
    --to-spacing-section: 24px;

    /* 阴影 */
    --to-shadow-card: 0 2px 8px rgba(15, 23, 42, 0.06);
    --to-shadow-hover: 0 6px 20px rgba(37, 99, 235, 0.12);

    /* 尺寸 */
    --to-sidebar-width: 260px;
    --to-header-height: 72px;
    /* 文章卡片最大宽度（参照编辑器阅读宽度） */
    --to-article-max-width: 820px;
}

/* ========== 页面容器 - 全屏三栏 ========== */
body.tutorial-page {
    overflow: hidden;
    background: #fff;
}

.tutorial-home-container {
    width: 100%;
    max-width: 100%;
    margin: 0;
    padding: 0;
    background: #fff;
    height: calc(100vh - var(--to-header-height));
    display: flex;
    flex-direction: row;
    overflow: hidden;
}

/* ========== 左侧目录栏 ========== */
/* 教程详情页独立侧边栏样式（不依赖 SidebarSnippet，无 CSS 冲突） */
.tutorial-home-container .sidebar {
    width: var(--to-sidebar-width);
    flex-shrink: 0;
    background: #fff;
    border-right: 2px solid #e0e0e0;
    overflow: hidden;
    height: 100%;
    display: flex;
    flex-direction: column;
    border-radius: 0;
    box-shadow: none;
    padding: 0;
    position: static;
    top: auto;
    max-height: none;
    align-self: stretch;
}

/* 隐藏 SidebarSnippet 标题 */
.tutorial-home-container .sidebar-title,
.tutorial-home-container .sidebar-title-icon {
    display: none !important;
}

/* 首页链接 */
.tutorial-home-container .sidebar-home-link {
    padding: 14px 20px;
    background: var(--to-primary-light);
    border-bottom: 1px solid var(--to-border);
    display: flex;
    align-items: center;
    gap: 8px;
    cursor: pointer;
    transition: background 0.2s;
    font-size: 15px;
    font-weight: 600;
    color: var(--to-primary);
    border-left: 3px solid var(--to-primary);
    flex-shrink: 0;
}
.tutorial-home-container .sidebar-home-link:hover {
    background: var(--to-primary-light);
}

/* 搜索栏 */
.tutorial-home-container .sidebar-search {
    padding: 12px 16px;
    border-bottom: 1px solid var(--to-border);
    position: relative;
    flex-shrink: 0;
}
.tutorial-home-container .sidebar-search::before {
    content: '';
    position: absolute;
    left: 26px;
    top: 50%;
    transform: translateY(-50%);
    width: 14px;
    height: 14px;
    border: 2px solid var(--to-text-placeholder);
    border-radius: 50%;
    pointer-events: none;
    z-index: 1;
}
.tutorial-home-container .sidebar-search::after {
    content: '';
    position: absolute;
    left: 36px;
    top: calc(50% + 5px);
    width: 6px;
    height: 2px;
    background: var(--to-text-placeholder);
    transform: rotate(45deg);
    pointer-events: none;
    z-index: 1;
}
.tutorial-home-container .sidebar-search-input {
    width: 100%;
    padding: 8px 12px 8px 36px;
    font-size: 13px;
    border: 1px solid var(--to-border);
    border-radius: var(--to-radius-input);
    outline: none;
    transition: border-color 0.18s, box-shadow 0.18s, background 0.18s;
    box-sizing: border-box;
    background: var(--to-bg-hover);
}
.tutorial-home-container .sidebar-search-input:focus {
    border-color: var(--to-primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
    background: #fff;
}
.tutorial-home-container .sidebar-search-input::placeholder {
    color: var(--to-text-placeholder);
}

/* 搜索结果 */
.tutorial-home-container .sidebar-search-results {
    display: none;
    padding: 4px 0;
    max-height: 300px;
    overflow-y: auto;
}
.tutorial-home-container .sidebar-search-results.active {
    display: block;
}
.tutorial-home-container .search-result-item {
    padding: 8px 20px;
    font-size: 13px;
    color: var(--to-text-secondary);
    cursor: pointer;
    transition: background 0.18s, color 0.18s;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}
.tutorial-home-container .search-result-item:hover {
    background: var(--to-bg-hover);
    color: var(--to-primary);
}
.tutorial-home-container .search-result-empty {
    padding: 20px 16px;
    font-size: 13px;
    color: var(--to-text-placeholder);
    text-align: center;
}
.tutorial-home-container .search-highlight {
    color: var(--to-primary);
    font-weight: 600;
}

/* 目录树容器 */
.tutorial-home-container .sidebar-tree {
    display: flex;
    flex-direction: column;
    gap: 2px;
    flex: 1;
    min-height: 0;
    overflow-y: auto;
    scrollbar-width: thin;
    -ms-overflow-style: none;
    padding: 8px 0;
}
.tutorial-home-container .sidebar-tree::-webkit-scrollbar {
    width: 6px;
    display: block;
}
.tutorial-home-container .sidebar-tree::-webkit-scrollbar-thumb {
    background: #d0d0d0;
    border-radius: 3px;
}
.tutorial-home-container .sidebar-tree::-webkit-scrollbar-thumb:hover {
    background: #b0b0b0;
}

/* 4级导航模块 - 卡片式 */
.tutorial-home-container .tree-module {
    margin: 2px 8px;
    border-radius: var(--to-radius-button);
    overflow: visible;
    transition: background 0.18s;
}
.tutorial-home-container .tree-module:hover {
    background: var(--to-bg-hover);
}
.tutorial-home-container .tree-module-header {
    display: flex;
    align-items: center;
    padding: 10px 12px;
    font-size: 14px;
    font-weight: 600;
    color: var(--to-text-main);
    border-radius: var(--to-radius-button);
    cursor: pointer;
    transition: background 0.18s, color 0.18s;
    border-left: 3px solid transparent;
}
.tutorial-home-container .tree-module-header:hover {
    background: var(--to-bg-hover);
}
.tutorial-home-container .tree-module-header.active {
    background: var(--to-primary-light);
    color: var(--to-primary);
    border-left-color: var(--to-primary);
}
.tutorial-home-container .tree-arrow {
    width: 18px;
    height: 18px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    transition: transform 0.2s;
    font-size: 12px;
    color: var(--to-text-muted);
}
.tutorial-home-container .tree-arrow.expanded {
    transform: rotate(90deg);
}
.tutorial-home-container .tree-module-name {
    flex: 1;
}
.tutorial-home-container .tree-articles {
    display: none;
    padding-left: 0;
}
.tutorial-home-container .tree-articles.expanded {
    display: block;
}

/* 文章列表项 */
.tutorial-home-container .tree-article-item {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 8px 12px 8px 30px;
    font-size: 13px;
    color: var(--to-text-secondary);
    cursor: pointer;
    transition: background 0.18s, color 0.18s;
    border-radius: 6px;
    margin: 1px 4px;
}
.tutorial-home-container .tree-article-item:hover {
    background: var(--to-bg-hover);
    color: var(--to-primary);
}
.tutorial-home-container .tree-article-item.active {
    background: var(--to-primary-light);
    color: var(--to-primary);
}
.tutorial-home-container .tree-article-lock {
    font-size: 12px;
    color: var(--to-primary);
    flex-shrink: 0;
}
.tutorial-home-container .tree-article-title {
    flex: 1;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

/* 覆盖 SidebarSnippet 蓝色主题 */
.tutorial-home-container .sidebar-section-label {
    color: var(--to-text-muted) !important;
}
.tutorial-home-container .sidebar-item {
    color: var(--to-text-secondary) !important;
    border-left: 3px solid transparent !important;
    border-radius: 0 !important;
    margin: 0 !important;
}
.tutorial-home-container .sidebar-item:hover {
    background: var(--to-bg-hover) !important;
    color: var(--to-primary) !important;
    border-left-color: var(--to-primary) !important;
    transform: none !important;
}
.tutorial-home-container .sidebar-item.active {
    background: var(--to-primary-light) !important;
    color: var(--to-primary) !important;
    border-left-color: var(--to-primary) !important;
    box-shadow: none !important;
    transform: none !important;
}
.tutorial-home-container .sidebar-item.active::after {
    display: none !important;
}
.tutorial-home-container .sidebar-item-count {
    color: var(--to-text-muted) !important;
    background: var(--to-bg-hover) !important;
}
.tutorial-home-container .sidebar-item.active .sidebar-item-count {
    background: var(--to-primary-light) !important;
    color: var(--to-primary) !important;
}
.tutorial-home-container .sidebar-footer {
    border-top: 1px solid var(--to-border) !important;
    background: var(--to-bg-hover) !important;
}
.tutorial-home-container .sidebar-footer-btn {
    background: #fff !important;
    color: var(--to-text-secondary) !important;
    border-color: var(--to-border) !important;
}
.tutorial-home-container .sidebar-footer-btn:hover {
    background: var(--to-primary-light) !important;
    color: var(--to-primary) !important;
    border-color: var(--to-primary) !important;
}
.tutorial-home-container .sidebar-filter .sidebar-item::before {
    background: var(--to-primary) !important;
}

/* ========== 中间列 ========== */
.tutorial-home-container .middle-column {
    flex: 1;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    min-width: 0;
    background: var(--to-bg-page);
}

/* ========== 顶部 Banner - 圆角卡片（参照 codefather.cn 课程头图） ========== */
.tutorial-home-container .tutorial-banner {
    background: #fff;
    border-radius: var(--to-radius-card);
    padding: 0;
    margin: var(--to-spacing-page) var(--to-spacing-page) 0;
    overflow: hidden;
    box-shadow: var(--to-shadow-card);
    border: 1px solid var(--to-border);
    display: flex;
    min-height: 200px;
    flex-shrink: 0;
    transition: opacity 0.3s, max-height 0.3s, margin 0.3s, padding 0.3s, border 0.3s;
}
/* 文章模式下隐藏 Banner */
.tutorial-home-container.middle-article-mode .tutorial-banner {
    display: none;
}

.tutorial-banner-cover {
    flex: 0 0 280px;
    background: linear-gradient(135deg, var(--to-primary) 0%, var(--to-primary-hover) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    position: relative;
}
/* 封面区装饰圆 */
.tutorial-banner-cover::before {
    content: '';
    position: absolute;
    top: -30px;
    right: -30px;
    width: 120px;
    height: 120px;
    background: rgba(255,255,255,0.08);
    border-radius: 50%;
}
.tutorial-banner-cover::after {
    content: '';
    position: absolute;
    bottom: -40px;
    left: -20px;
    width: 100px;
    height: 100px;
    background: rgba(255,255,255,0.06);
    border-radius: 50%;
}
.tutorial-banner-cover img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}
.banner-cover-placeholder {
    font-size: 72px;
    font-weight: 700;
    color: rgba(255, 255, 255, 0.9);
    text-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
    position: relative;
    z-index: 1;
}
.tutorial-banner-info {
    flex: 1;
    padding: 28px 32px;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}
.tutorial-banner-title {
    font-size: 28px;
    font-weight: 700;
    color: var(--to-text-main);
    margin-bottom: 12px;
    line-height: 1.4;
}
.tutorial-banner-summary {
    font-size: 15px;
    color: var(--to-text-secondary);
    line-height: 1.8;
    margin-bottom: 20px;
    flex: 1;
}
.tutorial-banner-meta {
    display: flex;
    align-items: center;
    gap: var(--to-spacing-card);
    flex-wrap: wrap;
}
.tutorial-meta-item {
    display: flex;
    align-items: center;
    gap: 6px;
    font-size: 14px;
    color: var(--to-text-secondary);
}
.tutorial-meta-label {
    color: var(--to-text-muted);
}
.tutorial-price-box {
    display: flex;
    align-items: baseline;
    gap: 8px;
}
.tutorial-price-original {
    font-size: 14px;
    color: var(--to-text-muted);
    text-decoration: line-through;
}
.tutorial-price-current {
    font-size: 24px;
    font-weight: 700;
    background: var(--to-paid-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}
.tutorial-price-free {
    font-size: 18px;
    font-weight: 600;
    color: var(--to-primary);
}
.tutorial-price-tag {
    display: inline-block;
    padding: 4px 10px;
    border-radius: var(--to-radius-tag);
    font-size: 12px;
    font-weight: 600;
}
.tutorial-price-tag.free {
    background: var(--to-primary-light);
    color: var(--to-primary);
    border: 1px solid var(--to-primary-border);
}
.tutorial-price-tag.paid {
    background: var(--to-paid-gradient);
    color: #fff;
    border: 1px solid var(--to-paid-border);
    cursor: pointer;
    text-decoration: none;
}
.tutorial-vip-btn {
    display: inline-block;
    padding: 6px 18px;
    border-radius: 6px;
    font-size: 14px;
    font-weight: 600;
    background: linear-gradient(135deg, #F59E0B 0%, #D97706 100%);
    color: #fff;
    text-decoration: none;
    margin-left: 12px;
    transition: all 0.2s;
    cursor: pointer;
}
.tutorial-vip-btn:hover {
    opacity: 0.9;
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(245, 158, 11, 0.3);
}

/* ========== Tab 栏 ========== */
.tutorial-home-container .tutorial-tabs {
    background: #fff;
    padding: 0 var(--to-spacing-page);
    margin: 0;
    border-bottom: 1px solid var(--to-border);
    display: flex;
    gap: 8px;
    flex-shrink: 0;
}
/* 文章模式下隐藏 Tab 栏 */
.tutorial-home-container.middle-article-mode .tutorial-tabs {
    display: none;
}
.tutorial-tab-item {
    flex: 0 0 auto;
    text-align: center;
    padding: 14px 28px;
    font-size: 16px;
    font-weight: 600;
    color: var(--to-text-secondary);
    cursor: pointer;
    transition: color 0.2s, background 0.2s;
    border-bottom: 3px solid transparent;
    border-radius: var(--to-radius-button) var(--to-radius-button) 0 0;
}
.tutorial-tab-item:hover {
    color: var(--to-primary);
    background: var(--to-bg-hover);
}
.tutorial-tab-item.active {
    color: var(--to-primary);
    border-bottom-color: var(--to-primary);
    background: transparent;
}

/* ========== 中间内容区 ========== */
/* 首页模式：内容区白底卡片 */
.tutorial-home-container .main-content {
    flex: 1;
    background: #fff;
    padding: var(--to-spacing-section) 28px;
    min-height: 0;
    height: 100%;
    overflow-y: auto;
    scrollbar-width: none;
    -ms-overflow-style: none;
}
/* 文章模式：中间列整体白底（两侧间隙与卡片同色，参照 codefather.cn） */
.tutorial-home-container.middle-article-mode .middle-column {
    background: #fff;
}
/* 文章模式：内容区白底 */
.tutorial-home-container.middle-article-mode .main-content {
    background: #fff;
    padding: 20px 0;
}
.tutorial-home-container .main-content::-webkit-scrollbar {
    display: none;
}

/* 文章卡片包裹层 — 居中白色卡片，参照 codefather.cn 文章详情页
 * 两侧间隙为白底，卡片通过 max-width 限制阅读宽度，不加阴影（与间隙同色） */
.article-card-wrapper {
    max-width: var(--to-article-max-width);
    margin: 0 auto;
    background: #fff;
    border-radius: 0;
    box-shadow: none;
    padding: 0 48px 40px;
    min-height: calc(100% - 40px);
}
/* 文章模式下返回按钮也放入卡片内，但贴顶部 */
.article-toolbar.visible ~ .article-card-wrapper {
    margin-top: 0;
}
/* 首页模式（介绍Tab、目录Tab）不需要卡片包裹，直接白底 */
.tutorial-home-container:not(.middle-article-mode) .article-card-wrapper {
    max-width: none;
    margin: 0;
    background: transparent;
    box-shadow: none;
    padding: 0;
    border-radius: 0;
}

/* 介绍 Tab 内容 */
.tutorial-intro-content {
    font-size: 15px;
    line-height: 2.0;
    color: var(--to-text-main);
}
.tutorial-intro-content > p:first-child {
    font-size: 16px;
    color: var(--to-text-secondary);
    line-height: 1.9;
    margin-bottom: 24px;
    padding: 20px 24px;
    background: var(--to-bg-hover);
    border-radius: 10px;
    border-left: 4px solid var(--to-primary);
}
.tutorial-intro-content p {
    margin-bottom: 16px;
}

/* 教程目录 Tab - 模块卡片 */
.module-overview {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
    gap: var(--to-spacing-card);
    padding: 4px 0;
}
.module-card {
    background: #fff;
    border: 1px solid var(--to-border);
    border-radius: var(--to-radius-card);
    padding: 20px;
    cursor: pointer;
    transition: border-color 0.25s, box-shadow 0.25s, transform 0.25s;
    position: relative;
    overflow: hidden;
}
.module-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background: linear-gradient(180deg, var(--to-primary) 0%, var(--to-primary-hover) 100%);
    opacity: 0;
    transition: opacity 0.25s;
}
.module-card:hover {
    border-color: var(--to-primary);
    box-shadow: var(--to-shadow-hover);
    transform: translateY(-3px);
}
.module-card:hover::before {
    opacity: 1;
}
.module-card-icon {
    width: 40px;
    height: 40px;
    border-radius: 10px;
    background: linear-gradient(135deg, var(--to-primary-light) 0%, #FFFBF3 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 18px;
    font-weight: 700;
    color: var(--to-primary);
    margin-bottom: 12px;
}
.module-card-name {
    font-size: 15px;
    font-weight: 600;
    color: var(--to-text-main);
    margin-bottom: 6px;
    line-height: 1.4;
}
.module-card-count {
    font-size: 13px;
    color: var(--to-text-muted);
    display: flex;
    align-items: center;
    gap: 4px;
}
.module-card-count::before {
    content: '';
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--to-primary);
    display: inline-block;
}

/* 教程目录 Tab - 竖向手风琴章节列表（参照 codefather.cn 课程目录） */
.catalog-chapter-list {
    display: flex;
    flex-direction: column;
    gap: 0;
    padding: 4px 0;
}
.catalog-chapter {
    border: 1px solid var(--to-border);
    border-radius: var(--to-radius-button);
    overflow: hidden;
    margin-bottom: 8px;
}
.catalog-chapter:last-child {
    margin-bottom: 0;
}
/* 章节标题栏 — 灰色背景，参照 codefather.cn */
.catalog-chapter-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 12px 16px;
    background: var(--to-bg-hover);
    cursor: pointer;
    transition: background 0.2s, color 0.2s;
    user-select: none;
}
.catalog-chapter-header:hover {
    background: #EBF5F0;
}
.catalog-chapter-header.expanded {
    background: var(--to-primary-light);
    border-bottom: 1px solid var(--to-border);
}
.catalog-chapter-name {
    font-size: 16px;
    font-weight: 600;
    color: var(--to-text-main);
}
.catalog-chapter-header.expanded .catalog-chapter-name {
    color: var(--to-primary);
}
.catalog-chapter-info {
    display: flex;
    align-items: center;
    gap: 8px;
}
.catalog-chapter-count {
    font-size: 12px;
    color: var(--to-text-muted);
}
.catalog-chapter-arrow {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 18px;
    height: 18px;
    font-size: 12px;
    color: var(--to-text-muted);
    transition: transform 0.2s;
    transform: rotate(0deg);
}
.catalog-chapter-arrow.expanded {
    transform: rotate(180deg);
}
/* 章节下文章列表 */
.catalog-article-list {
    display: none;
}
.catalog-article-list.expanded {
    display: block;
}
/* 文章列表项 — 带序号、标题、元信息，虚线分隔 */
.catalog-article-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 16px;
    cursor: pointer;
    transition: background 0.18s, color 0.18s;
    border-bottom: 1px dashed var(--to-border);
}
.catalog-article-item:last-child {
    border-bottom: none;
}
.catalog-article-item:hover {
    background: var(--to-primary-light);
}
.catalog-article-num {
    flex-shrink: 0;
    width: 24px;
    height: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 12px;
    font-weight: 600;
    color: var(--to-text-muted);
    background: var(--to-bg-hover);
    border-radius: 50%;
}
.catalog-article-item:hover .catalog-article-num {
    color: var(--to-primary);
    background: var(--to-primary-light);
}
.catalog-article-title {
    flex: 1;
    font-size: 15px;
    font-weight: 500;
    color: var(--to-text-main);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}
.catalog-article-item:hover .catalog-article-title {
    color: var(--to-primary);
}
.catalog-article-meta {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-shrink: 0;
}
.catalog-article-lock {
    font-size: 12px;
}
.catalog-article-views {
    font-size: 12px;
    color: var(--to-text-muted);
}
.catalog-article-empty {
    padding: 16px;
    font-size: 13px;
    color: var(--to-text-muted);
    text-align: center;
}

/* 文章列表区 */
.article-section {
    display: none;
}
.article-section.active {
    display: block;
}
.article-section-title {
    font-size: 18px;
    font-weight: 600;
    color: var(--to-text-main);
    margin-bottom: 16px;
    padding-bottom: 12px;
    border-bottom: 2px solid var(--to-primary);
    display: inline-block;
}
.article-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}
.article-item {
    background: #fff;
    border: 1px solid var(--to-border);
    border-radius: 10px;
    padding: 16px;
    cursor: pointer;
    transition: border-color 0.2s, box-shadow 0.2s, transform 0.2s;
}
.article-item:hover {
    border-color: var(--to-primary);
    box-shadow: 0 4px 16px rgba(37, 99, 235, 0.1);
    transform: translateY(-2px);
}
.article-item-body {
    display: flex;
    flex-direction: column;
    gap: 8px;
}
.article-item-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 8px;
}
.article-item-title {
    font-size: 15px;
    font-weight: 600;
    color: var(--to-text-main);
    line-height: 1.4;
    flex: 1;
}
.article-item-tag {
    display: inline-block;
    padding: 2px 8px;
    border-radius: var(--to-radius-tag);
    font-size: 12px;
    font-weight: 600;
}
.tag-paid {
    background: var(--to-paid-gradient);
    color: #fff;
    border: 1px solid var(--to-paid-border);
}
.tag-free {
    background: var(--to-primary-light);
    color: var(--to-primary);
    border: 1px solid var(--to-primary-border);
}
.article-item-summary {
    font-size: 14px;
    color: var(--to-text-secondary);
    line-height: 1.6;
}
.article-item-meta {
    display: flex;
    gap: 16px;
    font-size: 13px;
    color: var(--to-text-muted);
}

/* ========== 文章查看器 ========== */
.article-viewer {
    display: none;
}
.article-viewer.active {
    display: block;
}

/* 返回按钮 — 放在左侧间隙左上角，不进入卡片宽度限制 */
.article-toolbar {
    display: none;
    max-width: none;
    margin: 0 0 16px;
    padding: 0 48px;
}
.article-toolbar.visible {
    display: block;
}
.article-back-btn {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    padding: 6px 0;
    font-size: 14px;
    font-weight: 500;
    color: var(--to-text-secondary);
    background: transparent;
    border: none;
    cursor: pointer;
    transition: color 0.2s;
}
.article-back-btn:hover {
    color: var(--to-primary);
}
.article-back-arrow {
    font-size: 18px;
    line-height: 1;
}

/* 底部翻页按钮 — 放在卡片内底部，带文章标题 */
.article-nav-footer {
    display: none;
    justify-content: space-between;
    align-items: center;
    margin-top: 48px;
    padding-top: 24px;
    border-top: 1px solid var(--to-border);
    gap: 16px;
}
.article-nav-footer.visible {
    display: flex;
}
.article-nav-btn {
    display: flex;
    flex-direction: column;
    gap: 4px;
    padding: 12px 20px;
    font-size: 14px;
    color: var(--to-text-secondary);
    background: var(--to-bg-hover);
    border: 1px solid var(--to-border);
    border-radius: var(--to-radius-button);
    cursor: pointer;
    transition: background 0.2s, color 0.2s, border-color 0.2s;
    max-width: 48%;
    text-align: left;
}
.article-nav-btn:hover {
    background: var(--to-primary-light);
    color: var(--to-primary);
    border-color: var(--to-primary);
}
.article-nav-btn:disabled {
    opacity: 0.4;
    cursor: not-allowed;
}
/* 翻页按钮内的方向标签 */
.article-nav-btn-dir {
    font-size: 13px;
    color: var(--to-text-muted);
}
.article-nav-btn:hover .article-nav-btn-dir {
    color: var(--to-primary);
}
/* 翻页按钮内的文章标题 */
.article-nav-btn-title {
    font-size: 14px;
    font-weight: 500;
    color: var(--to-text-main);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}
.article-nav-btn:hover .article-nav-btn-title {
    color: var(--to-primary);
}
/* 下一页按钮靠右对齐 */
#navNextBtn {
    text-align: right;
    align-items: flex-end;
}

/* 加载状态 */
.loading {
    text-align: center;
    padding: 40px;
    font-size: 16px;
    color: var(--to-text-muted);
}

/* 文章正文 — 在卡片包裹层内 */
/* 文章标题（H1级别，参照 codefather.cn 文章详情页） */
.article-detail-title {
    font-size: 28px;
    font-weight: 700;
    color: var(--to-text-main);
    line-height: 1.4;
    margin-bottom: 16px;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--to-border);
}
/* 文章元信息（作者、时间、阅读量） */
.article-detail-meta {
    display: flex;
    align-items: center;
    gap: 16px;
    margin-bottom: 32px;
    font-size: 14px;
    color: var(--to-text-muted);
}
.article-detail-meta-item {
    display: flex;
    align-items: center;
    gap: 4px;
}

#article-content {
    font-size: 15px;
    line-height: 28px;
    color: var(--to-text-main);
}
#article-content h2 {
    font-size: 24px;
    font-weight: 600;
    margin: 36px 0 16px;
    padding-bottom: 10px;
    border-bottom: 1px solid var(--to-border);
}
#article-content h3 {
    font-size: 20px;
    font-weight: 600;
    margin: 28px 0 12px;
}
#article-content p {
    margin-bottom: 18px;
}
/* 表格 - GitHub/MDN 风：去竖线、底部横线、斑马纹、圆角（与 article.css 保持一致）*/
#article-content table {
    width: 100%;
    border-collapse: separate;
    border-spacing: 0;
    margin: 16px 0;
    border-radius: 8px;
    overflow: hidden;
    border: 1px solid #E2E8F0;
    box-shadow: 0 1px 3px rgba(15,23,42,0.04);
}
#article-content th, #article-content td {
    padding: 12px 16px;
    text-align: left;
    font-size: 14px;
    line-height: 1.6;
    border-bottom: 1px solid #E2E8F0;
    border-right: none;
    border-left: none;
    border-top: none;
}
#article-content tr:last-child td {
    border-bottom: none;
}
#article-content th {
    background: #fff;
    font-weight: 600;
    color: #0F172A;
    border-bottom: 2px solid #FA8C16;
}
/* 斑马纹 */
#article-content tbody tr:nth-child(even) td {
    background: #FFFBF3;
}
/* hover 行高亮 */
#article-content tbody tr:hover td {
    background: #FFF7E6;
}
#article-content pre {
    position: relative;
    margin: 18px 0;
    padding: 44px 0 18px; /* 左右内边距由 wrapper 控制 */
    background: #F6F8FA;
    border-radius: 8px;
    overflow-x: auto;
    border: 1px solid #E1E4E8;
    box-shadow: 0 1px 2px rgba(27,31,35,0.04);
    font-size: 13.5px;
    line-height: 1.65;
    font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}
/* 顶部装饰栏：mac 风格三个小圆点 + 浅色横条（与 article.css 统一） */
#article-content pre::before {
    content: '';
    position: absolute;
    left: 0;
    right: 0;
    top: 0;
    height: 32px;
    background: #F1F3F5;
    border-bottom: 1px solid #E1E4E8;
    border-radius: 8px 8px 0 0;
}
#article-content pre::after {
    content: '';
    position: absolute;
    left: 14px;
    top: 11px;
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: #FF5F56;
    box-shadow:
        18px 0 0 #FFBD2E,
        36px 0 0 #27C93F;
    z-index: 1;
}

/* 代码块复制按钮 */
#article-content pre .copy-btn {
    position: absolute;
    top: 6px;
    right: 10px;
    z-index: 10;
    padding: 4px 10px;
    font-size: 12px;
    line-height: 1;
    color: #656D76;
    background: rgba(255,255,255,0.7);
    border: 1px solid #E1E4E8;
    border-radius: 4px;
    cursor: pointer;
    opacity: 0;
    transition: opacity 0.2s, background 0.2s, color 0.2s;
    font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", sans-serif;
    user-select: none;
    -webkit-user-select: none;
}
#article-content pre:hover .copy-btn {
    opacity: 1;
}
#article-content pre .copy-btn:hover {
    background: #FA8C16;
    color: #fff;
    border-color: #FA8C16;
}
#article-content pre .copy-btn.copied {
    background: #27C93F;
    color: #fff;
    border-color: #27C93F;
    opacity: 1;
}

/* 代码块内部布局：左侧行号 + 右侧代码 */
#article-content pre .code-block-wrapper {
    display: flex;
    padding: 0 20px;
}
#article-content pre .code-block-wrapper .line-numbers {
    flex-shrink: 0;
    width: 40px;
    padding-right: 16px;
    margin-right: 16px;
    text-align: right;
    color: #8C959F;
    user-select: none;
    border-right: 1px solid #E1E4E8;
    line-height: 1.65;
}
#article-content pre .code-block-wrapper .line-numbers span {
    display: block;
}
#article-content pre .code-block-wrapper code {
    flex: 1;
    min-width: 0;
    white-space: pre;
    background: transparent;
    padding: 0;
    border: none;
    color: #24292E;
    font-size: inherit;
    font-family: inherit;
    line-height: inherit;
}

#article-content code {
    background: #EFF1F3;
    padding: 2px 7px;
    border-radius: 6px;
    font-size: 13.5px;
    color: #24292E;
    font-family: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
    border: 1px solid rgba(27,31,35,0.06);
}
#article-content pre code {
    background: transparent;
    border: none;
    padding: 0;
    color: #24292E;
    font-size: inherit;
    font-family: inherit;
    line-height: inherit;
    white-space: pre;
    word-break: normal;
    word-wrap: normal;
}

/* highlight.js GitHub 主题样式 */
#article-content .hljs {
    color: #24292E;
    background: transparent;
    font-family: Consolas, "Liberation Mono", Menlo, Courier, monospace;
}
#article-content .hljs-comment, #article-content .hljs-quote {
    color: #6A737D;
    font-style: italic;
}
#article-content .hljs-keyword, #article-content .hljs-selector-tag, #article-content .hljs-literal, #article-content .hljs-section, #article-content .hljs-link {
    color: #D73A49;
}
#article-content .hljs-function, #article-content .hljs-title, #article-content .hljs-name {
    color: #6F42C1;
}
#article-content .hljs-string, #article-content .hljs-attr, #article-content .hljs-symbol, #article-content .hljs-bullet, #article-content .hljs-addition {
    color: #22863A;
}
#article-content .hljs-number, #article-content .hljs-meta, #article-content .hljs-built_in, #article-content .hljs-builtin-name, #article-content .hljs-variable, #article-content .hljs-template-variable, #article-content .hljs-type {
    color: #005CC5;
}
#article-content .hljs-tag, #article-content .hljs-params {
    color: #22863A;
}

/* ========== 右侧栏 - 大纲 + 推荐 ========== */
.tutorial-home-container .aside-recommend {
    width: var(--to-sidebar-width);
    flex-shrink: 0;
    display: flex;
    flex-direction: column;
    height: 100%;
    overflow-y: auto;
    scrollbar-width: none;
    -ms-overflow-style: none;
    border-left: 2px solid #e0e0e0;
    background: #fff;
}
.tutorial-home-container .aside-recommend::-webkit-scrollbar {
    display: none;
}

/* 首页模式：隐藏大纲，只显示推荐 */
.aside-recommend.home-mode .outline-card {
    display: none;
}
/* 文章模式：隐藏推荐，只显示大纲 */
.aside-recommend.article-mode .recommend-card {
    display: none;
}

.outline-card,
.recommend-card {
    background: #fff;
    padding: 20px 16px;
    border-bottom: 1px solid var(--to-border);
}
.outline-title,
.recommend-header {
    font-size: 16px;
    font-weight: 600;
    color: var(--to-text-main);
    margin-bottom: 14px;
    display: flex;
    align-items: center;
    gap: 6px;
}
.recommend-icon {
    font-size: 16px;
}
.outline-list {
    list-style: none;
    padding: 0;
    margin: 0;
}
.outline-item {
    padding: 8px 0 8px 14px;
    font-size: 14px;
    color: var(--to-text-secondary);
    cursor: pointer;
    transition: color 0.2s, border-color 0.2s, background 0.2s;
    border-left: 2px solid transparent;
    border-radius: 0 4px 4px 0;
}
.outline-item:hover {
    color: var(--to-primary);
    border-left-color: #FFE7BA;
    background: #FFFBF3;
}
.outline-item.active {
    color: #D46B08;
    border-left-color: var(--to-primary);
    background: #FFF7E6;
    font-weight: 500;
}
.outline-empty {
    padding: 12px 0;
    font-size: 14px;
    color: var(--to-text-muted);
    text-align: center;
}
/* 推荐教程卡片化 — 参照 codefather.cn 右侧推荐课程 */
.recommend-item {
    display: flex;
    gap: 10px;
    padding: 10px;
    border: 1px solid var(--to-border);
    border-radius: var(--to-radius-button);
    margin-bottom: 10px;
    cursor: pointer;
    transition: border-color 0.2s, box-shadow 0.2s, transform 0.2s;
    overflow: hidden;
    text-decoration: none;
    color: inherit;
}
.recommend-item:last-child {
    margin-bottom: 0;
}
.recommend-item:hover {
    border-color: var(--to-primary);
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.1);
    transform: translateY(-2px);
}
/* 封面图区域 */
.recommend-item-cover {
    flex-shrink: 0;
    width: 64px;
    height: 64px;
    border-radius: 6px;
    overflow: hidden;
    background: linear-gradient(135deg, var(--to-primary) 0%, var(--to-primary-hover) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
}
.recommend-item-cover img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}
.recommend-cover-placeholder {
    font-size: 28px;
    font-weight: 700;
    color: rgba(255, 255, 255, 0.9);
    text-shadow: 0 1px 4px rgba(0, 0, 0, 0.1);
}
/* 内容区域 */
.recommend-item-body {
    flex: 1;
    min-width: 0;
    display: flex;
    flex-direction: column;
    gap: 4px;
    justify-content: space-between;
}
.recommend-item-title {
    font-size: 14px;
    font-weight: 600;
    color: var(--to-text-main);
    line-height: 1.4;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}
.recommend-item-summary {
    font-size: 12px;
    color: var(--to-text-muted);
    line-height: 1.5;
    overflow: hidden;
    text-overflow: ellipsis;
    display: -webkit-box;
    -webkit-line-clamp: 1;
    -webkit-box-orient: vertical;
}
/* 价格标签行 */
.recommend-item-price {
    display: flex;
    align-items: center;
    gap: 6px;
    margin-top: 2px;
}
.recommend-tag {
    display: inline-block;
    padding: 1px 6px;
    border-radius: 3px;
    font-size: 11px;
    font-weight: 600;
    line-height: 1.5;
}
.recommend-tag.tag-free {
    background: var(--to-primary-light);
    color: var(--to-primary);
    border: 1px solid var(--to-primary-border);
}
.recommend-tag.tag-paid {
    background: var(--to-paid-gradient);
    color: #fff;
    border: 1px solid var(--to-paid-border);
}
.recommend-tag.tag-vip {
    background: linear-gradient(135deg, #FA8C16 0%, #D46B08 100%);
    color: #fff;
    border: 1px solid #D46B08;
}
.recommend-student-count {
    font-size: 11px;
    color: var(--to-text-muted);
}

/* ========== 通用 ========== */
.tutorial-home-container .hidden {
    display: none !important;
}
.tutorial-home-container .empty-state {
    text-align: center;
    padding: 40px;
    font-size: 14px;
    color: var(--to-text-muted);
}

/* ========== Tab 内容 ========== */
.tab-content {
    display: none;
}
.tab-content.active {
    display: block;
}