/* ============================================================
   教学工作台 · 上课应用
   Apple 风格 · Action Blue
   ============================================================ */

:root {
  /* 色彩系统 */
  --bg: #F5F5F7;            /* 工作区背景 */
  --surface: #FFFFFF;       /* 卡片/侧栏/顶栏 */
  --border: #E0E0E0;        /* 1px 描边 */
  --accent: #0066CC;        /* Action Blue 强调色 */
  --accent-soft: #E8F1FA;   /* 导航激活底色 */
  --text: #1D1D1F;          /* 主文字 */
  --text-2: #7A7A7A;        /* 次要文字 */
  --red: #FF3B30;
  --green: #34A853;

  /* 圆角 */
  --r-card: 18px;
  --r-pill: 999px;
  --r-ctrl: 18px;

  /* 阴影 */
  --shadow-page: 0 3px 30px rgba(0, 0, 0, 0.22);

  /* 字体 */
  --font: "Inter", -apple-system, "SF Pro Text", "Segoe UI", "PingFang SC",
          "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
}

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

html, body {
  width: 100%;
  height: 100%;
  overflow: hidden;
  font-family: var(--font);
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}

button {
  font-family: inherit;
  border: none;
  background: none;
  cursor: pointer;
  color: inherit;
  outline: none;
}

/* ============================================================
   界面容器
   ============================================================ */
.screen {
  position: fixed;
  inset: 0;
  display: none;
  background: var(--surface);
}
.screen.active { display: flex; }

/* ============================================================
   侧栏（240px）
   ============================================================ */
.sidebar {
  width: 240px;
  flex: 0 0 240px;
  height: 100%;
  background: var(--surface);
  display: flex;
  flex-direction: column;
  padding: 20px;
  transition: flex-basis 0.25s ease, width 0.25s ease;
  overflow: hidden;
}
.sidebar.collapsed {
  width: 72px;
  flex-basis: 72px;
  padding: 20px 16px;
  align-items: center;
}
.sidebar.collapsed .app-name,
.sidebar.collapsed .section-label,
.sidebar.collapsed .nav-label { display: none; }
.sidebar.collapsed .nav-item { padding: 0; width: 40px; }
.sidebar.collapsed .nav-item .nav-ico { margin: 0; }
.sidebar.collapsed .collapse-btn { transform: rotate(180deg); }
.sidebar.collapsed .logo-row { justify-content: center; gap: 0; padding-bottom: 20px; }
.sidebar.collapsed .logo-mark,
.sidebar.collapsed .spacer { display: none; }

.logo-row {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 4px 0 24px;
  width: 100%;
}
.logo-mark {
  width: 32px;
  height: 32px;
  flex: 0 0 32px;
  background: var(--accent);
  border-radius: 8px;
  position: relative;
}
.logo-mark::before,
.logo-mark::after {
  content: "";
  position: absolute;
  width: 6.9px;
  height: 12px;
  border: 1.6px solid #fff;
  border-radius: 1.5px;
  top: 9px;
}
.logo-mark::before { left: 8.2px; }
.logo-mark::after  { left: 16.9px; }

.app-name {
  font-size: 16px;
  font-weight: 600;
  color: var(--text);
  white-space: nowrap;
}
.spacer { flex: 1; }

.collapse-btn {
  width: 32px;
  height: 32px;
  flex: 0 0 32px;
  background: var(--bg);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: transform 0.25s ease;
}
.collapse-btn .icon-arrow-left { color: var(--text); }

.nav-section {
  display: flex;
  flex-direction: column;
  gap: 2px;
  width: 100%;
}
.section-label {
  font-size: 12px;
  color: var(--text-2);
  padding: 12px 10px 8px;
  display: block;
  white-space: nowrap;
}
.nav-item {
  display: flex;
  align-items: center;
  gap: 10px;
  width: 100%;
  height: 40px;
  padding: 0 10px;
  border-radius: 10px;
  font-size: 14px;
  font-weight: 500;
  color: var(--text);
  white-space: nowrap;
  transition: background 0.15s ease;
}
.nav-item:hover { background: rgba(0, 102, 204, 0.06); }
.nav-item.active {
  background: var(--accent-soft);
  color: var(--accent);
}
.nav-ico { display: inline-flex; color: var(--text); }
.nav-item.active .nav-ico { color: var(--accent); }

.sidebar-footer { margin-top: auto; }

/* ============================================================
   内容区
   ============================================================ */
.content {
  flex: 1;
  min-width: 0;
  height: 100%;
  background: var(--bg);
  display: flex;
  flex-direction: column;
}

.top-bar {
  height: 72px;
  flex: 0 0 72px;
  background: var(--surface);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 24px;
}
.left-group { display: flex; align-items: center; gap: 14px; }
.title-col { display: flex; flex-direction: column; gap: 2px; }
.page-title {
  font-size: 24px;
  font-weight: 600;
  line-height: 1.2;
}
.page-subtitle { font-size: 13px; color: var(--text-2); }
.bar-title { font-size: 17px; font-weight: 600; line-height: 1.2; }
.bar-meta { font-size: 13px; color: var(--text-2); }

.right-col { display: flex; align-items: center; gap: 12px; }
.tools { display: flex; align-items: center; gap: 12px; }

/* 搜索框 */
.search {
  width: 280px;
  height: 40px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r-pill);
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 0 14px;
}
.search .icon-search { color: var(--text-2); flex: 0 0 24px; }
.search-input {
  flex: 1;
  min-width: 0;
  border: none;
  background: none;
  outline: none;
  font-family: inherit;
  font-size: 13px;
  color: var(--text);
}

/* 主按钮（胶囊） */
.btn-primary {
  height: 40px;
  background: var(--accent);
  border-radius: var(--r-pill);
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 0 18px;
  color: #fff;
  font-size: 13px;
  font-weight: 500;
  white-space: nowrap;
  transition: filter 0.15s ease;
}
.btn-primary:hover { filter: brightness(1.08); }
.btn-primary:active { filter: brightness(0.94); }

/* 次级按钮（描边胶囊） */
.btn-secondary {
  height: 40px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r-pill);
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 0 18px;
  color: var(--text);
  font-size: 13px;
  font-weight: 500;
  white-space: nowrap;
  transition: border-color 0.15s ease, color 0.15s ease;
}
.btn-secondary:hover { border-color: var(--accent); color: var(--accent); }
.btn-secondary:active { filter: brightness(0.97); }

/* 圆形图标按钮 */
.icon-btn {
  width: 36px;
  height: 36px;
  flex: 0 0 36px;
  background: var(--bg);
  border-radius: 18px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: filter 0.15s ease;
}
.icon-btn:hover { filter: brightness(0.95); }

/* ============================================================
   卡片网格
   ============================================================ */
.card-grid {
  flex: 1;
  overflow-y: auto;
  display: flex;
  flex-wrap: wrap;
  align-content: flex-start;
  gap: 20px;
  padding: 24px;
}
.card {
  position: relative;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r-card);
  overflow: hidden;
  cursor: pointer;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}
.card:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 24px rgba(0, 0, 0, 0.1);
}
.card:active { transform: translateY(0); }

/* 教材卡 273×280（信息区空间充足，标题两行+元信息一行） */
.book-card { width: 273px; height: 280px; }
.book-cover {
  width: 100%;
  height: 190px;
  position: relative;
  overflow: hidden;
}
/* 封面：PDF 第一页渲染（未上传封面时隐藏，露出渐变占位） */
.cover-img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: contain;
  background: #fff;
}
.cover-img[src=""],
.cover-img:not([src]) { display: none; }

/* 状态徽标（左上角，纵向堆叠，互不重叠） */
.card-badges {
  position: absolute;
  top: 10px;
  left: 10px;
  z-index: 3;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 6px;
  pointer-events: none;
}

/* 多选复选框（左上角，仅批量模式下出现） */
.card-check {
  position: absolute;
  top: 8px;
  left: 8px;
  z-index: 5;
  width: 24px;
  height: 24px;
  opacity: 0;
  transition: opacity 0.15s ease;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  pointer-events: none;
}
.card-grid.bulk-mode .card-check { opacity: 1; pointer-events: auto; }
.card.selected .card-check { opacity: 1; pointer-events: auto; }
.card-check input {
  width: 20px;
  height: 20px;
  margin: 0;
  accent-color: var(--accent);
  cursor: pointer;
}
.card.selected { outline: 2px solid var(--accent); outline-offset: -2px; }

/* 右下角更多操作按钮（悬停显示；悬停弹出菜单） */
.card-more {
  position: absolute;
  right: 10px;
  bottom: 10px;
  z-index: 6;
  width: 26px;
  height: 26px;
  border-radius: 8px;
  background: rgba(29, 29, 31, 0.78);
  color: #fff;
  font-size: 13px;
  line-height: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transition: opacity 0.15s ease, background 0.15s ease;
  cursor: pointer;
}
.card:hover .card-more { opacity: 1; }
.card-more:hover { background: var(--accent); }
.card-menu {
  position: absolute;
  right: 0;
  bottom: 32px;
  min-width: 100px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  box-shadow: 0 10px 28px rgba(0, 0, 0, 0.16);
  padding: 4px;
  display: none;
  flex-direction: column;
}
/* 桥接区：覆盖按钮与菜单之间的间隙，移动鼠标不会导致菜单消失 */
.card-menu::after {
  content: '';
  position: absolute;
  left: -6px;
  right: -6px;
  bottom: -12px;
  height: 12px;
}
.card-more:hover .card-menu,
.card-menu:hover { display: flex; }
.menu-item {
  height: 30px;
  padding: 0 12px;
  border-radius: 7px;
  font-size: 12px;
  font-weight: 500;
  text-align: left;
  color: var(--text);
  white-space: nowrap;
}
.menu-item:hover { background: var(--accent-soft); color: var(--accent); }
.menu-item.danger:hover { background: rgba(255, 59, 48, 0.1); color: var(--red); }
.shared-badge,
.conv-badge,
.cached-badge,
.cat-badge {
  height: 22px;
  padding: 0 9px;
  border-radius: 999px;
  color: #fff;
  font-size: 10px;
  font-weight: 600;
  display: flex;
  align-items: center;
  white-space: nowrap;
}
.shared-badge { background: rgba(52, 168, 83, 0.92); }
.conv-badge   { background: rgba(122, 122, 122, 0.88); }
.cached-badge { background: rgba(0, 102, 204, 0.92); }
.cat-badge    { background: rgba(224, 169, 79, 0.92); }
.cached-badge[hidden] { display: none; }

/* 操作按钮（右上角横排，悬停显示；共享中按钮常显绿色） */
.card-actions {
  position: absolute;
  top: 10px;
  right: 10px;
  z-index: 4;
  display: flex;
  gap: 6px;
  opacity: 0;
  transition: opacity 0.15s ease;
}
.card:hover .card-actions { opacity: 1; }
.card-actions button {
  height: 26px;
  padding: 0 10px;
  border-radius: 999px;
  background: rgba(29, 29, 31, 0.78);
  color: #fff;
  font-size: 11px;
  font-weight: 500;
  display: flex;
  align-items: center;
  gap: 4px;
  white-space: nowrap;
}
.card-actions button:hover { background: var(--accent); }
.card-actions .card-share.on { background: var(--green); }
.card-actions .card-conv { background: var(--accent); }
.card-actions .card-conv:disabled { opacity: 0.6; }
.card-actions .card-cat { background: rgba(224, 169, 79, 0.85); }
.card-actions .card-del { width: 26px; padding: 0; justify-content: center; }
.card-del .icon-trash { width: 14px; height: 14px; }

/* 分类筛选下拉 */
.cat-select {
  height: 40px;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 0 12px;
  font-family: inherit;
  font-size: 13px;
  color: var(--text);
  background: var(--surface);
  outline: none;
  cursor: pointer;
}
.cat-select:focus { border-color: var(--accent); }

/* 分类分组头（占整行，可点击折叠） */
.cat-group-head {
  width: 100%;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 4px 2px 2px;
  cursor: pointer;
  user-select: none;
}
.cat-group-head:hover .cat-group-name { color: var(--accent); }
.cat-arrow {
  width: 0;
  height: 0;
  border-left: 5px solid var(--text-2);
  border-top: 4px solid transparent;
  border-bottom: 4px solid transparent;
  transform: rotate(90deg);
  transition: transform 0.15s ease;
}
.cat-group-head.collapsed .cat-arrow { transform: rotate(0deg); }
.cat-group-name { font-size: 14px; font-weight: 600; }
.cat-group-count {
  min-width: 20px;
  height: 20px;
  padding: 0 6px;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 11px;
  font-weight: 600;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* 批量操作悬浮条（批量模式下浮于右上角，不占布局空间） */
.bulk-bar {
  position: fixed;
  top: 88px;
  right: 24px;
  z-index: 900;
  min-width: 300px;
  padding: 10px 16px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 14px;
  box-shadow: 0 14px 40px rgba(0, 0, 0, 0.22);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
}
.bulk-count { font-size: 13px; font-weight: 600; white-space: nowrap; }
.bulk-actions { display: flex; gap: 8px; align-items: center; }
/* 条内按钮大小统一 */
.bulk-bar button {
  height: 32px;
  padding: 0 14px;
  border-radius: 9px;
  font-size: 13px;
  font-weight: 500;
}

/* 下载教材时显示的封面大图 */
.cover-big {
  max-width: 70%;
  max-height: 80%;
  object-fit: contain;
  border-radius: 8px;
  box-shadow: var(--shadow-page);
  background: #fff;
}

/* 秒上传任务卡：封面上的进度覆盖层 */
.job-overlay {
  position: absolute;
  inset: 0;
  z-index: 2;
  background: rgba(29, 29, 31, 0.55);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 12px;
  padding: 0 28px;
}
.job-text {
  color: #fff;
  font-size: 14px;
  font-weight: 600;
  white-space: nowrap;
}
.job-track {
  width: 100%;
  height: 6px;
  background: rgba(255, 255, 255, 0.25);
  border-radius: 3px;
  overflow: hidden;
}
.job-fill {
  height: 100%;
  width: 0;
  background: #fff;
  border-radius: 3px;
  transition: width 0.2s ease;
}
.job-card .book-text { opacity: 0.85; }

/* 上传进度浮层 */
#uploadBar {
  position: fixed;
  top: 76px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 1500;
  width: 340px;
  background: rgba(29, 29, 31, 0.92);
  border-radius: 12px;
  padding: 12px 16px;
  color: #fff;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s ease;
}
#uploadBar.show { opacity: 1; }
.ub-text {
  font-size: 12px;
  margin-bottom: 8px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.ub-track {
  height: 4px;
  background: rgba(255, 255, 255, 0.2);
  border-radius: 2px;
  overflow: hidden;
}
.ub-fill {
  height: 100%;
  width: 0;
  background: var(--accent);
  border-radius: 2px;
  transition: width 0.15s ease;
}
.book-text {
  padding: 12px 14px;
  display: flex;
  flex-direction: column;
  gap: 5px;
  flex: 1;
  min-height: 0;
}
.book-title {
  font-size: 15px;
  font-weight: 600;
  line-height: 1.35;
  overflow: hidden;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
}
.book-meta {
  font-size: 12px;
  color: var(--text-2);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* 封面渐变配色 */
.cover-1 { background: linear-gradient(135deg, #7FB2E5, #4A7FB5); }
.cover-2 { background: linear-gradient(135deg, #8FD3A8, #57A87C); }
.cover-3 { background: linear-gradient(135deg, #F0A98C, #DE7E5B); }
.cover-4 { background: linear-gradient(135deg, #9B9BE0, #6D6DC2); }
.cover-5 { background: linear-gradient(135deg, #6FC5C0, #47A29D); }
.cover-6 { background: linear-gradient(135deg, #F2C879, #E0A94F); }
.cover-7 { background: linear-gradient(135deg, #E88B93, #D4626C); }
.cover-8 { background: linear-gradient(135deg, #A8C98E, #82AF66); }

/* 课件卡 381×262（缩略图 160 + 信息区约 102，标题两行+元信息完整显示） */
.cw-card { width: 381px; height: 262px; }
.cw-thumb {
  width: 100%;
  height: 160px;
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
}
.thumb-title {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px 32px;
  font-size: 16px;
  font-weight: 600;
  color: var(--text);
  text-align: center;
  line-height: 1.5;
  z-index: 1;
}
/* 首页预览封面：真实渲染课件第一页并等比缩小 */
.thumb-preview {
  position: absolute;
  inset: 0;
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  pointer-events: none;
  z-index: 2;
  background: var(--surface);
}
.thumb-preview iframe {
  width: 1920px;
  height: 1080px;
  border: 0;
  background: #fff;
  flex: 0 0 auto;
  transform-origin: center center;
}
.cw-badge {
  position: absolute;
  bottom: 10px;
  left: 10px;
  background: var(--surface);
  border-radius: 6px;
  padding: 0 8px;
  height: 22px;
  display: flex;
  align-items: center;
  font-size: 10px;
  font-weight: 600;
  color: var(--accent);
  z-index: 3;
}
.cw-text {
  padding: 12px 14px;
  display: flex;
  flex-direction: column;
  gap: 4px;
  min-height: 0;
}
.cw-title {
  font-size: 15px;
  font-weight: 600;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  line-height: 1.4;
}
.cw-meta { font-size: 13px; color: var(--text-2); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }

/* 课件缩略图配色 */
.thumb-1 { background: #E8F1FA; }
.thumb-2 { background: #E6F6EA; }
.thumb-3 { background: #FEF3E8; }
.thumb-4 { background: #F3ECFA; }
.thumb-5 { background: #EDF0FD; }
.thumb-6 { background: #E4F7F5; }
.thumb-7 { background: #FDECEC; }
.thumb-8 { background: #FDF6E6; }

/* 空态 */
.empty-state {
  width: 100%;
  height: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 12px;
  color: var(--text-2);
  font-size: 14px;
}
.empty-ico {
  width: 60px;
  height: 60px;
  border-radius: 18px;
  background: var(--surface);
  border: 1px dashed var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-2);
}
.empty-ico .icon-book { width: 26px; height: 26px; }

/* ============================================================
   放映区（B）
   ============================================================ */
.viewer {
  flex: 1;
  min-height: 0;
  background: var(--bg);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 20px;
  padding: 24px;
  position: relative;
}

/* PDF 容器（双页展示，左右分布） */
.pdf-slot {
  position: relative;
  flex: 1;
  width: 100%;
  min-height: 0;
  display: flex;
}
.pdf-slot .pdf-wrap {
  flex: 1;
  width: 100%;
  min-height: 0;
}
.pdf-wrap {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 20px;
}
.pdf-wrap canvas {
  display: block;
  background: #fff;
  border-radius: 4px;
  box-shadow: var(--shadow-page);
}

/* 空态占位（placeholder 类存在时显示提示并隐藏内容） */
.pdf-wrap.placeholder canvas,
.courseware-slide.placeholder > *,
.fs-slide.placeholder > * { display: none; }

.pdf-wrap.placeholder::after,
.courseware-slide.placeholder::after,
.fs-slide.placeholder::after {
  content: attr(data-placeholder);
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-2);
  font-size: 15px;
  text-align: center;
  padding: 24px;
}

/* 全屏 PDF 容器 */
.fs-wrap {
  width: 100%;
  height: 100%;
  flex: none;
}

/* ============================================================
   控制条
   ============================================================ */
.control-bar {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r-ctrl);
  height: 56px;
  display: flex;
  align-items: center;
  gap: 24px;
  padding: 0 10px;
  align-self: center;
  flex: 0 0 auto;
}
.ctrl-btn {
  height: 40px;
  background: var(--bg);
  border-radius: var(--r-pill);
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 0 14px;
  font-size: 13px;
  font-weight: 500;
  color: var(--text);
}
.ctrl-btn.primary { background: var(--accent); color: #fff; }
.ctrl-btn:hover { filter: brightness(0.97); }
.ctrl-btn.primary:hover { filter: brightness(1.08); }

/* 页码指示（可输入跳转） */
.page-ind {
  min-width: 64px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 4px;
  font-size: 13px;
  color: var(--text-2);
  font-variant-numeric: tabular-nums;
}
.page-input {
  width: 52px;
  height: 30px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--surface);
  text-align: center;
  font-family: inherit;
  font-size: 13px;
  font-weight: 600;
  color: var(--text);
  outline: none;
  font-variant-numeric: tabular-nums;
  -moz-appearance: textfield;
  appearance: textfield;
}
.page-input::-webkit-outer-spin-button,
.page-input::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
.page-input:focus { border-color: var(--accent); }
.page-total { min-width: 24px; text-align: left; }

/* ============================================================
   课件放映（C）
   ============================================================ */
.stage {
  flex: 1;
  min-height: 0;
  background: var(--bg);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 20px;
  padding: 24px;
}
.courseware-slide {
  position: relative;
  width: 100%;
  flex: 1;
  min-height: 0;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r-card);
  box-shadow: var(--shadow-page);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 56px 64px;
  overflow: auto;
}

/* 幻灯片内容（HTML 课件的通用排版兜底，页面自带样式优先） */
.courseware-slide > * {
  max-width: 100%;
}
.courseware-slide :is(h1, h2, h3, h4) {
  line-height: 1.3;
  margin: 0.4em 0 0.5em;
  font-weight: 600;
}
.courseware-slide h1 { font-size: 40px; }
.courseware-slide h2 { font-size: 28px; }
.courseware-slide h3 { font-size: 22px; }
.courseware-slide :is(p, li, blockquote, figcaption) {
  font-size: 19px;
  line-height: 1.7;
  color: var(--text);
}
.courseware-slide ul, .courseware-slide ol {
  padding-left: 1.6em;
  margin: 0.5em 0;
}
.courseware-slide li { margin: 0.3em 0; }
.courseware-slide img {
  max-width: 100%;
  height: auto;
  border-radius: 8px;
}
.courseware-slide table {
  border-collapse: collapse;
  margin: 0.5em 0;
}
.courseware-slide td, .courseware-slide th {
  border: 1px solid var(--border);
  padding: 8px 14px;
  font-size: 16px;
}
.courseware-slide code {
  background: rgba(0, 0, 0, 0.06);
  border-radius: 5px;
  padding: 1px 6px;
  font-family: "SF Mono", Consolas, monospace;
  font-size: 0.92em;
}
.courseware-slide pre {
  background: #1D1D1F;
  color: #E8E8ED;
  border-radius: 12px;
  padding: 18px;
  overflow: auto;
}
.courseware-slide pre code { background: none; padding: 0; }

/* 整文档 iframe 放映：填满面板，不套用应用内排版 */
.courseware-slide.frame-mode {
  padding: 0;
  overflow: hidden;
}
.cw-frame {
  width: 100%;
  height: 100%;
  border: none;
  background: #fff;
  display: block;
}

/* ============================================================
   全屏放映（D）
   ============================================================ */
.rail {
  width: 72px;
  flex: 0 0 72px;
  height: 100%;
  background: var(--surface);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  padding: 16px 0;
}
.rail-logo {
  width: 32px;
  height: 32px;
  background: var(--accent);
  border-radius: 8px;
  position: relative;
}
.rail-logo::before,
.rail-logo::after {
  content: "";
  position: absolute;
  width: 6.9px;
  height: 12px;
  border: 1.6px solid #fff;
  border-radius: 1.5px;
  top: 9px;
}
.rail-logo::before { left: 8.2px; }
.rail-logo::after  { left: 16.9px; }
.rail-gap { height: 12px; }
.rail-btn {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.15s ease;
}
.rail-btn.active { background: var(--accent-soft); }
.rail-spacer { flex: 1; }

.fullscreen-stage {
  flex: 1;
  height: 100%;
  min-width: 0;
  background: var(--bg);
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 64px 80px 110px;
}
.fs-slide {
  position: relative;
  width: 100%;
  height: 100%;
  background: var(--surface);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 48px 80px;
  overflow: auto;
}
.fs-panel :is(p, li) { font-size: 24px; }
.fs-panel h1 { font-size: 52px; }
.fs-panel h2 { font-size: 34px; }
.fs-bar { position: absolute; bottom: 20px; left: 50%; transform: translateX(-50%); z-index: 5; }

/* ============================================================
   白板模式（F）
   ============================================================ */
.board-toolbar {
  width: 96px;
  flex: 0 0 96px;
  height: 100%;
  background: var(--surface);
  border-right: 1px solid #E8E8ED;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  padding: 16px 0;
}
.tool-btn {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.15s ease;
}
.tool-btn.active { background: var(--accent-soft); }
.tool-btn:hover { background: rgba(0, 102, 204, 0.08); }
.tool-gap { height: 12px; }

.color-stack, .weight-stack {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
}
.color-dot {
  width: 22px;
  height: 22px;
  border-radius: 50%;
  border: 2px solid transparent;
}
.color-dot.black { background: var(--text); }
.color-dot.red   { background: var(--red); }
.color-dot.blue  { background: var(--accent); }
.color-dot.green { background: var(--green); }
.color-dot.active { border-color: var(--accent); }

.weight {
  border-radius: 3px;
  background: var(--text);
  width: 40px;
}
.weight.thin  { height: 4px; border-radius: 2px; }
.weight.mid   { height: 6px; border-radius: 3px; }
.weight.thick { height: 9px; border-radius: 4.5px; }
.weight.active { box-shadow: 0 0 0 1.5px var(--accent); }

.exit-board {
  width: 64px;
  height: 40px;
  background: var(--accent);
  color: #fff;
  border-radius: var(--r-pill);
  font-size: 13px;
  font-weight: 500;
}

.board-stage {
  flex: 1;
  height: 100%;
  position: relative;
  background: var(--surface);
  overflow: hidden;
}
#boardCanvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  cursor: crosshair;
  touch-action: none;
}
.board-tag {
  position: absolute;
  top: 20px;
  left: 28px;
  font-size: 13px;
  color: var(--text-2);
  background: rgba(245, 245, 247, 0.85);
  border-radius: 999px;
  padding: 6px 14px;
  pointer-events: none;
}

/* ============================================================
   批注模式（G）
   ============================================================ */
.anno-toolbar {
  position: absolute;
  top: 72px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 20;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 26px;
  height: 52px;
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 0 6px;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.08);
}
.anno-toolbar .divider {
  width: 1px;
  height: 24px;
  background: var(--border);
}
.anno-colors { display: flex; align-items: center; gap: 8px; padding: 0 6px; }
.anno-colors .color-dot { width: 20px; height: 20px; }
.anno-weights { display: flex; align-items: center; gap: 8px; padding: 0 6px; }
.anno-weights .weight { width: 24px; }

/* B 屏就地批注：工具栏浮于放映区顶部（默认隐藏，进入批注时显示） */
.viewer .anno-toolbar { top: 16px; }
.anno-toolbar[hidden] { display: none; }
.btn-secondary.active {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-soft);
}
.anno-exit {
  height: 36px;
  background: var(--accent);
  color: #fff;
  border-radius: var(--r-pill);
  padding: 0 18px;
  font-size: 12px;
  font-weight: 500;
  white-space: nowrap;
}
.anno-exit:hover { filter: brightness(1.08); }

/* B 屏批注覆盖画布：与 PDF 画布同一坐标系，页面位置尺寸不变 */
#pdfAnnoCanvasB {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  display: none;
  z-index: 10;
  cursor: crosshair;
  touch-action: none;
}

/* ============================================================
   登录 / 注册层
   ============================================================ */
.login-overlay {
  position: fixed;
  inset: 0;
  z-index: 2000;
  background: rgba(245, 245, 247, 0.94);
  backdrop-filter: blur(10px);
  display: none;
  align-items: center;
  justify-content: center;
}
.login-card {
  width: 400px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 24px;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.12);
  padding: 48px 44px 40px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 14px;
}
.login-logo {
  width: 52px;
  height: 52px;
  background: var(--accent);
  border-radius: 14px;
  position: relative;
}
.login-logo::before,
.login-logo::after {
  content: "";
  position: absolute;
  width: 11px;
  height: 19px;
  border: 2.6px solid #fff;
  border-radius: 2px;
  top: 14px;
}
.login-logo::before { left: 14px; }
.login-logo::after  { left: 27px; }
.login-title { font-size: 24px; font-weight: 600; }
.login-sub { font-size: 13px; color: var(--text-2); margin-bottom: 10px; }
.login-tabs {
  display: flex;
  background: var(--bg);
  border-radius: var(--r-pill);
  padding: 4px;
  gap: 4px;
}
.login-tab {
  height: 34px;
  padding: 0 26px;
  border-radius: var(--r-pill);
  font-size: 13px;
  font-weight: 500;
  color: var(--text-2);
}
.login-tab.active { background: var(--surface); color: var(--accent); box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08); }
.login-input {
  width: 100%;
  height: 42px;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 0 14px;
  font-family: inherit;
  font-size: 14px;
  color: var(--text);
  outline: none;
  background: var(--surface);
}
.login-input:focus { border-color: var(--accent); }
.login-err {
  min-height: 18px;
  font-size: 12px;
  color: var(--red);
  text-align: center;
}
.login-btn { width: 100%; justify-content: center; height: 44px; font-size: 14px; margin-top: 4px; }

/* ============================================================
   我的库 / 共享库 切换
   ============================================================ */
.view-tabs {
  display: flex;
  background: var(--bg);
  border-radius: var(--r-pill);
  padding: 4px;
  gap: 4px;
  flex: 0 0 auto;
}
.view-tab {
  height: 32px;
  padding: 0 18px;
  border-radius: var(--r-pill);
  font-size: 13px;
  font-weight: 500;
  color: var(--text-2);
}
.view-tab.active { background: var(--surface); color: var(--accent); box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08); }

/* 图片模式：教材页面按页加载 */
.pdf-img {
  display: block;
  background: #fff;
  border-radius: 4px;
  box-shadow: var(--shadow-page);
}

/* ============================================================
   Toast 提示
   ============================================================ */
#toast {
  position: fixed;
  top: 84px;
  left: 50%;
  transform: translateX(-50%) translateY(-8px);
  z-index: 1000;
  background: rgba(29, 29, 31, 0.88);
  color: #fff;
  font-size: 13px;
  padding: 10px 20px;
  border-radius: 999px;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.25s ease, transform 0.25s ease;
  max-width: 80vw;
  text-align: center;
}
#toast.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* ============================================================
   管理后台
   ============================================================ */
[hidden] { display: none !important; }
.login-admin-link { font-size: 12px; color: var(--text-2); margin-top: 6px; }
.login-admin-link a { color: var(--accent); text-decoration: none; }
.login-admin-link a:hover { text-decoration: underline; }

.sidebar-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 18px 14px;
}
.sidebar-logo .login-logo { width: 36px; height: 36px; border-radius: 10px; flex: 0 0 36px; }
.sidebar-logo .login-logo::before,
.sidebar-logo .login-logo::after { width: 7px; height: 13px; top: 10px; border-width: 2px; }
.sidebar-logo .login-logo::before { left: 10px; }
.sidebar-logo .login-logo::after { left: 19px; }
.sidebar-title { font-size: 14px; font-weight: 600; }

.admin-nav { display: flex; flex-direction: column; gap: 6px; padding: 0 10px; }
.nav-btn {
  display: flex;
  align-items: center;
  gap: 10px;
  height: 40px;
  padding: 0 12px;
  border-radius: 10px;
  font-size: 14px;
  font-weight: 500;
  color: var(--text-2);
  text-align: left;
  width: 100%;
}
.nav-btn:hover { background: var(--bg); color: var(--text); }
.nav-btn.active { background: var(--accent-soft); color: var(--accent); font-weight: 600; }
.nav-btn .icon-book, .nav-btn .icon-clock, .nav-btn .icon-settings { width: 18px; height: 18px; flex: 0 0 18px; }

.admin-me {
  padding: 12px 14px;
  display: flex;
  flex-direction: column;
  gap: 2px;
}
.admin-name { font-size: 14px; font-weight: 600; }
.admin-mode { font-size: 11px; color: var(--text-2); }

.admin-panel { display: flex; flex-direction: column; gap: 18px; min-width: 0; }
.admin-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 18px;
  box-shadow: var(--shadow-card);
}
.admin-card-title { font-size: 14px; font-weight: 600; margin-bottom: 12px; }
.admin-tip { font-size: 12px; color: var(--text-2); margin: 0 0 12px; }

.admin-table-wrap { overflow-x: auto; }
.admin-table { width: 100%; border-collapse: collapse; font-size: 13px; }
.admin-table th {
  text-align: left;
  font-size: 12px;
  font-weight: 600;
  color: var(--text-2);
  padding: 8px 10px;
  border-bottom: 1px solid var(--border);
  white-space: nowrap;
}
.admin-table td { padding: 10px; border-bottom: 1px solid var(--border); white-space: nowrap; }
.admin-table tr:last-child td { border-bottom: none; }
.admin-table tr:hover td { background: var(--bg); }
.cell-strong { font-weight: 600; }
.cell-actions { display: flex; gap: 8px; }
.admin-empty { padding: 28px 0; text-align: center; font-size: 13px; color: var(--text-2); }

.mini-btn {
  height: 28px;
  padding: 0 10px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 12px;
  color: var(--text);
  background: var(--surface);
}
.mini-btn:hover { border-color: var(--accent); color: var(--accent); }
.mini-btn.danger:hover { border-color: var(--red); color: var(--red); }

.switch-btn {
  width: 36px;
  height: 20px;
  border-radius: 10px;
  background: #D8D8DE;
  position: relative;
  transition: background 0.2s ease;
}
.switch-btn::after {
  content: "";
  position: absolute;
  top: 2px;
  left: 2px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: #fff;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.25);
  transition: left 0.2s ease;
}
.switch-btn.on { background: var(--accent); }
.switch-btn.on::after { left: 18px; }

.stat-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 14px;
}
.stat-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 20px;
  box-shadow: var(--shadow-card);
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.stat-num { font-size: 28px; font-weight: 700; color: var(--accent); }
.stat-label { font-size: 12px; color: var(--text-2); }

/* 弹窗 */
.modal {
  position: fixed;
  inset: 0;
  z-index: 1500;
  background: rgba(0, 0, 0, 0.35);
  display: flex;
  align-items: center;
  justify-content: center;
}
.modal-card {
  width: 360px;
  background: var(--surface);
  border-radius: 16px;
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.2);
}
.modal-title { font-size: 17px; font-weight: 600; margin: 0 0 4px; }
.modal-label { font-size: 12px; color: var(--text-2); }
.modal-actions { display: flex; justify-content: flex-end; gap: 10px; margin-top: 8px; }

/* ============================================================
   图标（SVG 内联 mask，24×24 描边风格）
   ============================================================ */
.icon-book,
.icon-slides,
.icon-clock,
.icon-settings,
.icon-search,
.icon-plus,
.icon-arrow-left,
.icon-arrow-right,
.icon-fullscreen,
.icon-zoom-in,
.icon-zoom-out,
.icon-play,
.icon-pen,
.icon-eraser,
.icon-undo,
.icon-trash,
.icon-download,
.icon-logout {
  display: inline-block;
  width: 24px;
  height: 24px;
  flex: 0 0 24px;
  mask-repeat: no-repeat;
  mask-position: center;
  mask-size: contain;
  -webkit-mask-repeat: no-repeat;
  -webkit-mask-position: center;
  -webkit-mask-size: contain;
  background-color: currentColor;
}

.icon-book      { -webkit-mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Crect x='3' y='5' width='7' height='14' rx='1.5' fill='none' stroke='black' stroke-width='1.8'/%3E%3Crect x='14' y='5' width='7' height='14' rx='1.5' fill='none' stroke='black' stroke-width='1.8'/%3E%3Cpath d='M10 5v14' stroke='black' stroke-width='1.8'/%3E%3C/svg%3E"); }
.icon-slides    { -webkit-mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Crect x='3' y='4' width='18' height='13' rx='2' fill='none' stroke='black' stroke-width='1.8'/%3E%3Cpath d='M9 21h6M12 17v4' stroke='black' stroke-width='1.8' stroke-linecap='round'/%3E%3C/svg%3E"); }
.icon-clock     { -webkit-mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Ccircle cx='12' cy='12' r='8.5' fill='none' stroke='black' stroke-width='1.8'/%3E%3Cpath d='M12 7.5V12l3 2' fill='none' stroke='black' stroke-width='1.8' stroke-linecap='round'/%3E%3C/svg%3E"); }
.icon-settings  { -webkit-mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Ccircle cx='12' cy='12' r='3' fill='none' stroke='black' stroke-width='1.8'/%3E%3Cpath d='M12 3v3M12 18v3M3 12h3M18 12h3M5.6 5.6l2.1 2.1M16.3 16.3l2.1 2.1M18.4 5.6l-2.1 2.1M7.7 16.3l-2.1 2.1' stroke='black' stroke-width='1.8' stroke-linecap='round'/%3E%3C/svg%3E"); }
.icon-search    { -webkit-mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Ccircle cx='10.5' cy='10.5' r='6.5' fill='none' stroke='black' stroke-width='1.8'/%3E%3Cpath d='M15.5 15.5L21 21' stroke='black' stroke-width='1.8' stroke-linecap='round'/%3E%3C/svg%3E"); }
.icon-plus      { -webkit-mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M12 5v14M5 12h14' stroke='black' stroke-width='2' stroke-linecap='round'/%3E%3C/svg%3E"); }
.icon-arrow-left  { -webkit-mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M19 12H5M11 6l-6 6 6 6' fill='none' stroke='black' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E"); }
.icon-arrow-right { -webkit-mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M5 12h14M13 6l6 6-6 6' fill='none' stroke='black' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E"); }
.icon-fullscreen { -webkit-mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M4 9V4h5M20 9V4h-5M4 15v5h5M20 15v5h-5' fill='none' stroke='black' stroke-width='1.8' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E"); }
.icon-zoom-in   { -webkit-mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Ccircle cx='10.5' cy='10.5' r='6.5' fill='none' stroke='black' stroke-width='1.8'/%3E%3Cpath d='M15.5 15.5L21 21M10.5 7.5v6M7.5 10.5h6' stroke='black' stroke-width='1.8' stroke-linecap='round'/%3E%3C/svg%3E"); }
.icon-zoom-out  { -webkit-mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Ccircle cx='10.5' cy='10.5' r='6.5' fill='none' stroke='black' stroke-width='1.8'/%3E%3Cpath d='M15.5 15.5L21 21M7.5 10.5h6' stroke='black' stroke-width='1.8' stroke-linecap='round'/%3E%3C/svg%3E"); }
.icon-play      { -webkit-mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M8 5.5v13l11-6.5z' fill='black'/%3E%3C/svg%3E"); }
.icon-pen       { -webkit-mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M4 20l1-4L16.5 4.5a2.1 2.1 0 013 3L8 19l-4 1z' fill='none' stroke='black' stroke-width='1.8' stroke-linejoin='round'/%3E%3Cpath d='M14.5 6.5l3 3' stroke='black' stroke-width='1.8'/%3E%3C/svg%3E"); }
.icon-eraser    { -webkit-mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M9 20h11M4.5 14.5l6-6M4.5 14.5a2 2 0 000 3l2.5 2.5a2 2 0 003 0l6-6a2 2 0 000-3l-4-4a2 2 0 00-3 0l-4.5 4.5a2 2 0 000 3z' fill='none' stroke='black' stroke-width='1.8' stroke-linejoin='round'/%3E%3C/svg%3E"); }
.icon-undo      { -webkit-mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M9 14L4 9l5-5' fill='none' stroke='black' stroke-width='1.8' stroke-linecap='round' stroke-linejoin='round'/%3E%3Cpath d='M4 9h10a6 6 0 010 12h-3' fill='none' stroke='black' stroke-width='1.8' stroke-linecap='round'/%3E%3C/svg%3E"); }
.icon-trash     { -webkit-mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M4 7h16M9 7V5a1 1 0 011-1h4a1 1 0 011 1v2M6.5 7l1 13a1 1 0 001 1h7a1 1 0 001-1l1-13' fill='none' stroke='black' stroke-width='1.8' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E"); }
.icon-download  { -webkit-mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M12 3v12M7 10l5 5 5-5M4 21h16' fill='none' stroke='black' stroke-width='1.8' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E"); }
.icon-logout    { -webkit-mask-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cpath d='M9 21H5a2 2 0 01-2-2V5a2 2 0 012-2h4M16 17l5-5-5-5M21 12H9' fill='none' stroke='black' stroke-width='1.8' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E"); }

/* 滚动条 */
::-webkit-scrollbar { width: 8px; height: 8px; }
::-webkit-scrollbar-thumb { background: #D8D8DE; border-radius: 4px; }
::-webkit-scrollbar-track { background: transparent; }