/* 全局变量（精准复刻Windows 11资源管理器） */
    :root {
        --win-blue: #0078D4; /* Windows 11官方文件夹蓝 */
        --win-blue-hover: #005A9E;
        --win-gray-10: #F8F8F8; /* 窗口背景 */
        --win-gray-20: #F2F2F2; /* 文件夹背景 */
        --win-gray-30: #E0E0E0; /* 边框色 */
        --win-gray-40: #D0D0D0; /* 分割线 */
        --win-gray-50: #EDEDED; /* 高亮背景 */
        --win-text-main: #1A1A1A; /* 主文本 */
        --win-text-gray: #666666; /* 次文本 */
        --win-text-light: #999999; /* 淡文本 */
        --win-border: 1px solid var(--win-gray-30); /* 系统边框 */
        --win-radius: 2px; /* Windows 11小圆角（几乎直角） */
        --win-shadow: 0 1px 2px rgba(0,0,0,0.04); /* 更细腻的阴影 */
        --win-shadow-hover: 0 2px 4px rgba(0,0,0,0.08); /* hover阴影 */
        --win-transition: all 0.2s ease-in-out; /* 更顺滑的过渡 */
        --sidebar-width: 220px; /* 侧边栏默认宽度 */
        --sidebar-collapsed-width: 0; /* 折叠后宽度 */
    }

    /* 重置样式（清空默认样式，还原系统原生感） */
    * {
        margin: 0;
        padding: 0;
        box-sizing: border-box;
    }

    body {
        font-family: "Segoe UI", "Microsoft Yahei", Arial, sans-serif; /* Windows 11默认字体 */
        color: var(--win-text-main);
        background-color: var(--win-gray-10);
        line-height: 1.4; /* 系统行高 */
        min-height: 100vh;
        display: flex;
        flex-direction: column;
        font-size: 13px; /* Windows 11默认字体大小 */
    }

    a {
        color: var(--win-blue);
        text-decoration: none;
        transition: var(--win-transition);
    }

    a:hover {
        color: var(--win-blue-hover);
        text-decoration: underline;
    }

    ul {
        list-style: none;
    }

    button {
        cursor: pointer;
        border: none;
        background: none;
        transition: var(--win-transition);
        font-family: "Segoe UI", sans-serif;
        font-size: 13px;
    }

    input:focus, select:focus {
        outline: 1px solid var(--win-blue);
        outline-offset: 0;
    }

    /* 自定义滚动条（Windows 11风格） */
    ::-webkit-scrollbar {
        width: 8px;
        height: 8px;
    }
    ::-webkit-scrollbar-track {
        background: var(--win-gray-10);
    }
    ::-webkit-scrollbar-thumb {
        background: var(--win-gray-30);
        border-radius: 4px;
    }
    ::-webkit-scrollbar-thumb:hover {
        background: var(--win-gray-40);
    }

    /* 容器（95%宽度，居中，贴合系统窗口） */
    .container {
        width: 95%;
        max-width: none;
        margin: 0 auto;
        padding: 0;
    }

    /* 头部（复刻Windows 11窗口标题栏） */
    header {
        background-color: #FFFFFF;
        border-bottom: var(--win-border);
        box-shadow: var(--win-shadow);
        position: sticky;
        top: 0;
        z-index: 999;
        height: 48px; /* Windows 11标题栏高度 */
        display: flex;
        align-items: center;
    }

    .header-wrap {
        width: 100%;
        display: flex;
        justify-content: space-between;
        align-items: center;
        padding: 0 10px;
    }

    /* 系统风格Logo（CSS绘制Windows文件夹图标） */
    .logo {
        display: flex;
        align-items: center;
        font-size: 14px;
        font-weight: 600;
        color: var(--win-text-main);
    }

    /* CSS绘制Windows 11文件夹图标（更细腻） */
    .folder-icon {
        width: 24px;
        height: 24px;
        margin-right: 8px;
        position: relative;
        background-color: var(--win-blue);
        border-radius: var(--win-radius);
        box-shadow: 0 1px 1px rgba(0,0,0,0.1);
    }

    .folder-icon::before {
        content: "";
        position: absolute;
        top: -4px;
        left: 0;
        width: 12px;
        height: 4px;
        background-color: var(--win-blue);
        border-top-left-radius: var(--win-radius);
        border-top-right-radius: var(--win-radius);
    }

    .top-nav {
        display: flex;
        align-items: center;
    }

    .top-nav li {
        position: relative;
        margin-left: 20px;
    }

    .top-nav a {
        font-size: 13px;
        color: var(--win-text-main);
        font-weight: 400;
        padding: 6px 0;
        display: block;
    }

    .top-nav a:hover {
        color: var(--win-blue);
        text-decoration: none;
    }

    .top-nav a::after {
        content: "";
        position: absolute;
        bottom: 0;
        left: 0;
        width: 0;
        height: 2px;
        background-color: var(--win-blue);
        transition: var(--win-transition);
    }

    .top-nav a:hover::after {
        width: 100%;
    }

    .mobile-menu {
        display: none;
        font-size: 18px;
        color: var(--win-text-main);
        padding: 4px 8px;
        border-radius: var(--win-radius);
    }
    .mobile-menu:hover {
        background-color: var(--win-gray-20);
    }

    /* Windows 11地址栏（面包屑导航）- 新增折叠按钮 */
    .address-bar {
        background-color: #FFFFFF;
        border-bottom: var(--win-border);
        padding: 6px 10px;
        display: flex;
        align-items: center;
        gap: 8px;
    }

    /* 侧边栏折叠/展开按钮 */
    .sidebar-toggle {
        width: 28px;
        height: 28px;
        border-radius: var(--win-radius);
        border: var(--win-border);
        background-color: #FFFFFF;
        display: flex;
        align-items: center;
        justify-content: center;
        font-size: 14px;
        color: var(--win-text-main);
        cursor: pointer;
        flex-shrink: 0;
    }
    .sidebar-toggle:hover {
        background-color: var(--win-gray-20);
        box-shadow: var(--win-shadow-hover);
    }

    .address-bar .breadcrumb {
        display: flex;
        align-items: center;
        gap: 4px;
        flex: 1;
    }

    .breadcrumb-item {
        display: flex;
        align-items: center;
        font-size: 13px;
    }
    .breadcrumb-item a {
        color: var(--win-blue);
    }
    .breadcrumb-item a:hover {
        text-decoration: underline;
    }

    .breadcrumb-sep {
        color: var(--win-text-light);
        margin: 0 4px;
        font-size: 11px;
    }

    .address-bar .search-box {
        width: 220px;
        padding: 4px 8px;
        border: var(--win-border);
        border-radius: var(--win-radius);
        background-color: var(--win-gray-10);
        display: flex;
        align-items: center;
        gap: 6px;
        transition: var(--win-transition);
    }
    .address-bar .search-box:hover {
        background-color: var(--win-gray-20);
    }

    .address-bar .search-box input {
        border: none;
        background: none;
        outline: none;
        font-size: 12px;
        width: 100%;
    }

    /* 主内容区（优化折叠过渡） */
    .main-wrap {
        display: flex;
        margin-top: 0;
        gap: 0;
        flex: 1;
        width: 100%;
        background-color: #FFFFFF;
        border: var(--win-border);
        border-top: none;
        transition: var(--win-transition);
    }

    /* 侧边栏（复刻Windows 11导航窗格 + 折叠功能） */
    .sidebar {
        width: var(--sidebar-width);
        background: var(--win-gray-10);
        border-right: var(--win-border);
        padding: 0;
        flex-shrink: 0;
        height: calc(100vh - 96px);
        position: sticky;
        top: 48px;
        overflow-y: auto;
        transition: var(--win-transition);
        opacity: 1;
    }
    /* 折叠状态 */
    .sidebar.collapsed {
        width: var(--sidebar-collapsed-width);
        opacity: 0;
        pointer-events: none;
    }

    /* 导航窗格分组标题（更细腻） */
    .sidebar-group-title {
        padding: 8px 12px;
        font-size: 12px;
        color: var(--win-text-gray);
        font-weight: 600;
        text-transform: uppercase;
        letter-spacing: 0.5px;
        border-bottom: var(--win-border);
        background-color: var(--win-gray-10);
        position: sticky;
        top: 0;
        z-index: 10;
    }

    /* 多级文件夹菜单（点击展开） */
    .sidebar-menu {
        width: 100%;
    }

    /* 一级文件夹（点击展开） */
    .menu-item {
        border-bottom: 1px solid transparent;
        position: relative;
    }

    .menu-item > a {
        display: flex;
        justify-content: space-between;
        align-items: center;
        padding: 7px 12px;
        border-radius: 0;
        color: var(--win-text-main);
        font-size: 13px;
        font-weight: 400;
        background: transparent;
        border: none;
        width: 100%;
        cursor: pointer;
    }

    .menu-item > a:hover {
        background-color: var(--win-gray-50);
        color: var(--win-blue);
        text-decoration: none;
        box-shadow: inset 0 0 0 1px rgba(0,120,212,0.1);
    }

    /* 修复图标和文字换行：核心 - 设为flex布局 */
    .menu-item > a .menu-content {
        display: flex;
        align-items: center;
        gap: 8px;
        white-space: nowrap;
    }

    /* CSS绘制文件夹子图标（更细腻） */
    .menu-icon {
        width: 16px;
        height: 16px;
        position: relative;
        background-color: var(--win-blue);
        border-radius: 1px;
        flex-shrink: 0;
        box-shadow: 0 1px 1px rgba(0,0,0,0.08);
    }

    .menu-icon::before {
        content: "";
        position: absolute;
        top: -2px;
        left: 0;
        width: 8px;
        height: 2px;
        background-color: var(--win-blue);
        border-top-left-radius: 1px;
        border-top-right-radius: 1px;
    }

    /* 二级文件夹专属图标（绿色 + 更细腻） */
    .menu-icon.sub {
        background-color: #009688;
        box-shadow: 0 1px 1px rgba(0,150,136,0.1);
    }
    .menu-icon.sub::before {
        background-color: #009688;
    }

    .menu-item > a .arrow {
        font-size: 9px;
        color: var(--win-text-gray);
        transition: var(--win-transition);
        flex-shrink: 0;
    }
    .menu-item.active > a .arrow {
        transform: rotate(90deg);
        color: var(--win-blue);
    }

    /* 二/三级文件夹容器（点击展开） */
    .submenu {
        max-height: 0;
        overflow: hidden;
        transition: max-height 0.2s ease;
        padding-left: 20px;
        margin-top: 0;
    }
    /* 只有active状态才展开 */
    .menu-item.active > .submenu {
        max-height: 1000px;
    }

    /* 二级文件夹（点击展开） */
    .submenu-item {
        margin-bottom: 0;
        position: relative;
    }
    .submenu-item > a {
        display: flex;
        justify-content: space-between;
        align-items: center;
        padding: 7px 12px;
        border-radius: 0;
        color: var(--win-text-main);
        font-size: 13px;
        border: none;
        width: 100%;
        cursor: pointer;
    }
    .submenu-item > a .menu-content {
        display: flex;
        align-items: center;
        gap: 8px;
        white-space: nowrap;
    }
    .submenu-item > a:hover {
        background-color: var(--win-gray-50);
        color: var(--win-blue);
        text-decoration: none;
        box-shadow: inset 0 0 0 1px rgba(0,120,212,0.1);
    }
    .submenu-item > a .arrow {
        font-size: 9px;
        color: var(--win-text-gray);
        transition: var(--win-transition);
        flex-shrink: 0;
    }
    .submenu-item.active > a .arrow {
        transform: rotate(90deg);
        color: var(--win-blue);
    }

    /* 三级文件夹（点击展开） */
    .submenu-level3 {
        max-height: 0;
        overflow: hidden;
        transition: max-height 0.2s ease;
        padding-left: 20px;
        margin-top: 0;
    }
    /* 只有active状态才展开 */
    .submenu-item.active > .submenu-level3 {
        max-height: 1000px;
    }
    .submenu-level3 li a {
        display: block;
        padding: 7px 12px;
        border-radius: 0;
        color: var(--win-text-main);
        font-size: 13px;
        border: none;
        white-space: nowrap;
        cursor: pointer;
    }
    .submenu-level3 li a:hover,
    .submenu-level3 li a.active {
        background-color: var(--win-gray-50);
        color: var(--win-blue);
        text-decoration: none;
        box-shadow: inset 0 0 0 1px rgba(0,120,212,0.1);
    }
    .submenu-level3 li a.active {
        background-color: rgba(0,120,212,0.08);
    }

    /* 内容区（折叠时自适应宽度） */
    .content {
        flex: 1;
        width: calc(100% - var(--sidebar-width));
        padding: 0;
        height: calc(100vh - 96px);
        overflow-y: auto;
        transition: var(--win-transition);
    }
    /* 侧边栏折叠后，内容区占满宽度 */
    .sidebar.collapsed + .content {
        width: 100%;
    }

    /* Windows 11工具栏（移除列表视图按钮） */
    .file-toolbar {
        padding: 6px 12px;
        border-bottom: var(--win-border);
        display: flex;
        justify-content: space-between;
        align-items: center;
        background-color: var(--win-gray-10);
    }
    .toolbar-actions {
        display: flex;
        gap: 8px;
        align-items: center;
    }
    .toolbar-btn {
        padding: 4px 10px;
        border-radius: var(--win-radius);
        border: var(--win-border);
        background-color: #FFFFFF;
        color: var(--win-text-main);
        font-size: 12px;
        transition: var(--win-transition);
    }
    .toolbar-btn:hover {
        background-color: var(--win-gray-20);
        box-shadow: var(--win-shadow-hover);
    }
    .toolbar-btn.active {
        background-color: var(--win-blue);
        color: #FFFFFF;
        border-color: var(--win-blue);
        box-shadow: inset 0 1px 2px rgba(0,0,0,0.1);
    }
    .toolbar-filter {
        display: flex;
        gap: 8px;
        align-items: center;
    }
    .filter-label {
        font-size: 12px;
        color: var(--win-text-gray);
    }
    .filter-select {
        padding: 4px 8px;
        border: var(--win-border);
        border-radius: var(--win-radius);
        background-color: #FFFFFF;
        font-size: 12px;
        outline: none;
        transition: var(--win-transition);
    }
    .filter-select:hover {
        border-color: var(--win-gray-40);
    }

    /* 搜索区（更细腻） */
    .search-section {
        background: transparent;
        border: none;
        box-shadow: none;
        padding: 12px 15px;
        margin-bottom: 0;
        border-bottom: var(--win-border);
    }
    .search-title {
        font-size: 16px;
        font-weight: 600;
        color: var(--win-text-main);
        margin-bottom: 10px;
        text-align: left;
        padding-left: 2px;
    }
    .search-box {
        display: flex;
        gap: 8px;
        max-width: 500px;
        margin: 0;
    }
    .search-input {
        flex: 1;
        padding: 7px 10px;
        border: var(--win-border);
        border-radius: var(--win-radius);
        font-size: 13px;
        color: var(--win-text-main);
        font-family: "Segoe UI", sans-serif;
        transition: var(--win-transition);
    }
    .search-input:hover {
        border-color: var(--win-gray-40);
    }
    .search-btn {
        padding: 0 18px;
        background-color: var(--win-blue);
        color: #FFFFFF;
        border-radius: var(--win-radius);
        font-size: 13px;
        font-weight: 400;
        transition: var(--win-transition);
    }
    .search-btn:hover {
        background-color: var(--win-blue-hover);
        box-shadow: var(--win-shadow-hover);
    }

    /* 版本筛选栏（更细腻） */
    .filter-bar {
        background: transparent;
        border: none;
        box-shadow: none;
        padding: 10px 15px;
        margin-bottom: 0;
        border-bottom: var(--win-border);
    }
    .filter-title {
        font-size: 12px;
        color: var(--win-text-gray);
        margin-bottom: 8px;
        display: flex;
        align-items: center;
    }
    .filter-title::before {
        content: "";
        display: inline-block;
        width: 14px;
        height: 14px;
        background-color: #FF9800;
        border-radius: 1px;
        margin-right: 5px;
        position: relative;
        box-shadow: 0 1px 1px rgba(255,152,0,0.1);
    }
    .filter-title::before::after {
        content: "";
        position: absolute;
        top: -2px;
        left: 0;
        width: 8px;
        height: 2px;
        background-color: #FF9800;
    }
    .filter-tags {
        display: flex;
        flex-wrap: wrap;
        gap: 8px;
    }
    .filter-tag {
        padding: 5px 12px;
        background: #FFFFFF;
        border: var(--win-border);
        border-radius: var(--win-radius);
        font-size: 12px;
        color: var(--win-text-main);
        cursor: pointer;
        transition: var(--win-transition);
    }
    .filter-tag:hover {
        background-color: var(--win-gray-20);
        border-color: var(--win-gray-40);
    }
    .filter-tag.active {
        background: var(--win-blue);
        color: #FFFFFF;
        border-color: var(--win-blue);
        box-shadow: inset 0 1px 2px rgba(0,0,0,0.1);
    }

    /* 教材列表（仅保留网格视图） */
    .book-list-section {
        background: transparent;
        border: none;
        box-shadow: none;
        padding: 15px;
    }
    .section-header {
        display: flex;
        justify-content: space-between;
        align-items: center;
        margin-bottom: 12px;
        padding-bottom: 8px;
        border-bottom: var(--win-border);
    }
    .section-title {
        font-size: 14px;
        font-weight: 600;
        color: var(--win-text-main);
        display: flex;
        align-items: center;
    }
    .section-title::before {
        content: "";
        display: inline-block;
        width: 16px;
        height: 16px;
        background-color: #4CAF50;
        border-radius: 1px;
        margin-right: 6px;
        position: relative;
        box-shadow: 0 1px 1px rgba(76,175,80,0.1);
    }
    .section-title::before::after {
        content: "";
        position: absolute;
        top: -2px;
        left: 0;
        width: 8px;
        height: 2px;
        background-color: #4CAF50;
    }
    .view-more {
        font-size: 12px;
        color: var(--win-blue);
        padding: 2px 4px;
        border-radius: var(--win-radius);
    }
    .view-more:hover {
        background-color: rgba(0,120,212,0.08);
        text-decoration: none;
    }

    /* Windows 11文件网格布局（仅保留这个） */
    .book-grid {
        display: grid;
        grid-template-columns: repeat(7, 1fr);
        gap: 12px;
        padding: 8px 0;
    }

    /* 网格视图-文件卡片（更细腻） */
    .book-card {
        border: none;
        border-radius: var(--win-radius);
        overflow: hidden;
        transition: var(--win-transition);
        background: transparent;
        padding: 6px;
    }
    .book-card:hover {
        transform: none;
        box-shadow: var(--win-shadow-hover);
        background-color: var(--win-gray-20);
        border-color: transparent;
    }
    .book-cover {
       /* height: 120px;*/
        background-color: var(--win-gray-10);
        display: flex;
        align-items: center;
        justify-content: center;
        overflow: hidden;
        border: none;
        margin-bottom: 6px;
        border-radius: var(--win-radius);
        box-shadow: inset 0 0 0 1px var(--win-gray-30);
    }
    .book-cover img {
        width: 95%;
        height: 95%;
        object-fit: contain;
        transition: var(--win-transition);
    }
    .book-card:hover .book-cover img {
        opacity: 0.95;
    }

    .book-info {
        padding: 0;
        text-align: center;
    }
    .book-name {
        font-size: 12px;
        font-weight: 400;
        color: var(--win-text-main);
        margin-bottom: 3px;
        white-space: nowrap;
        overflow: hidden;
        text-overflow: ellipsis;
    }
    .book-version {
        font-size: 11px;
        color: var(--win-text-gray);
        margin-bottom: 6px;
    }
    .book-actions {
        display: flex;
        gap: 6px;
        justify-content: center;
    }
    .download-btn, .preview-btn {
        flex: none;
        padding: 3px 10px;
        text-align: center;
        border-radius: var(--win-radius);
        font-size: 12px;
        border: var(--win-border);
        transition: var(--win-transition);
    }
    .download-btn {
        background-color: var(--win-blue);
        color: #FFFFFF;
        border-color: var(--win-blue);
    }
    .download-btn:hover {
        background-color: var(--win-blue-hover);
        box-shadow: var(--win-shadow-hover);
    }
    .preview-btn {
        border-color: var(--win-gray-30);
        color: var(--win-text-main);
        background: #FFFFFF;
    }
    .preview-btn:hover {
        background-color: var(--win-gray-20);
        box-shadow: var(--win-shadow-hover);
    }

    /* 底部（更细腻） */
    footer {
        background-color: var(--win-gray-10);
        border-top: var(--win-border);
        color: var(--win-text-gray);
        padding: 8px 0;
        margin-top: 0;
        font-size: 12px;
    }
    .footer-wrap {
        display: none;
    }
    .copyright {
        text-align: left;
        font-size: 12px;
        padding-top: 0;
        border-top: none;
        padding-left: 15px;
        line-height: 1.5;
    }

    /* 响应式适配（优化） */
    @media (max-width: 1200px) {
        .book-grid {
            grid-template-columns: repeat(3, 1fr);
        }
    }
    @media (max-width: 992px) {
        .book-grid {
            grid-template-columns: repeat(2, 1fr);
        }
    }
    @media (max-width: 768px) {
        .main-wrap {
            flex-direction: column;
        }
        .sidebar {
            width: 100%;
            height: auto;
            border-right: none;
            border-bottom: var(--win-border);
            position: static;
            top: auto;
        }
        .content {
            width: 100%;
            height: auto;
        }
        .sidebar.collapsed + .content {
            width: 100%;
        }
        .top-nav {
            display: none;
        }
        .mobile-menu {
            display: block;
        }
        .book-grid {
            grid-template-columns: repeat(2, 1fr);
        }
        .address-bar .search-box {
            display: none;
        }
    }
    @media (max-width: 480px) {
        .search-box {
            flex-direction: column;
        }
        .book-grid {
            grid-template-columns: 1fr;
        }
        .file-toolbar {
            flex-wrap: wrap;
            gap: 6px;
        }
        .toolbar-filter {
            margin-top: 6px;
            width: 100%;
        }
    }