/* ========================================
   Material You 色板（M3）
   ======================================== */
:root {
  --primary: #6750A4;
  --on-primary: #FFFFFF;
  --primary-container: #EADDFF;
  --on-primary-container: #21005D;

  --secondary: #625B71;
  --secondary-container: #E8DEF8;

  --tertiary: #7D5260;
  --tertiary-container: #FFD8E4;

  --surface: #FEF7FF;
  --surface-container-lowest: #FFFFFF;
  --surface-container-low: #F7F2FA;
  --surface-container: #F3EDF7;
  --surface-container-high: #ECE6F0;
  --surface-container-highest: #E6E0E9;

  --on-surface: #1C1B1F;
  --on-surface-variant: #49454F;
  --outline: #79747E;
  --outline-variant: #CAC4D0;

  --error: #B3261E;
  --on-error: #FFFFFF;

  --shadow-sm: 0 1px 2px rgba(0,0,0,0.04), 0 1px 3px rgba(0,0,0,0.06);
  --shadow-md: 0 2px 4px rgba(0,0,0,0.05), 0 4px 12px rgba(0,0,0,0.08);
  --shadow-lg: 0 4px 8px rgba(0,0,0,0.06), 0 12px 24px rgba(0,0,0,0.10);

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 28px;
  --radius-full: 999px;

  --transition: 200ms cubic-bezier(0.2, 0, 0, 1);
}

/* 暗色由 theme.js 把偏好(auto/light/dark)解析成 <html data-theme="dark|light">，
   故这里只需定义 dark 覆盖；auto 跟随系统的逻辑在 JS 里 matchMedia 处理。 */
:root[data-theme="dark"] {
    --primary: #D0BCFF;
    --on-primary: #381E72;
    --primary-container: #4F378B;
    --on-primary-container: #EADDFF;

    --secondary-container: #4A4458;
    --tertiary-container: #633B48;

    --surface: #141218;
    --surface-container-lowest: #0F0D13;
    --surface-container-low: #1D1B20;
    --surface-container: #211F26;
    --surface-container-high: #2B2930;
    --surface-container-highest: #36343B;

    --on-surface: #E6E1E5;
    --on-surface-variant: #CAC4D0;
    --outline: #938F99;
    --outline-variant: #49454F;

    --error: #F2B8B5;
    --on-error: #601410;

    --shadow-sm: 0 1px 2px rgba(0,0,0,0.2), 0 1px 3px rgba(0,0,0,0.3);
    --shadow-md: 0 2px 4px rgba(0,0,0,0.25), 0 4px 12px rgba(0,0,0,0.35);
    --shadow-lg: 0 4px 8px rgba(0,0,0,0.3), 0 12px 24px rgba(0,0,0,0.4);
}

/* ========================================
   基础
   ======================================== */
* { box-sizing: border-box; }

/* hidden 属性优先于任何 display 规则（修复书签面板/PDF 按钮的隐藏） */
[hidden] { display: none !important; }

html, body {
  margin: 0;
  padding: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
               "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", sans-serif;
  background: var(--surface);
  color: var(--on-surface);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

button { font-family: inherit; cursor: pointer; }
a { color: inherit; text-decoration: none; }
h1, h2, h3 { margin: 0; font-weight: 500; letter-spacing: -0.01em; }

.eyebrow {
  display: inline-block;
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--primary);
  margin-bottom: 8px;
}

.icon-btn {
  width: 40px;
  height: 40px;
  border: none;
  background: transparent;
  color: var(--on-surface);
  border-radius: var(--radius-full);
  font-size: 18px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: background-color var(--transition);
}
.icon-btn:hover { background: var(--surface-container-high); }

/* 统一线性图标（Phosphor 内联 SVG，fill:currentColor，尺寸由 data-icon-size / size 决定） */
.nbi { display: block; flex: none; }
.ic { display: inline-flex; align-items: center; justify-content: center; line-height: 0; }

/* ========================================
   首页（NotebookLM 风格）
   ======================================== */
body.home {
  min-height: 100vh;
  background: var(--surface-container-low);
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 20px 40px;
  max-width: 1360px;
  margin: 0 auto;
}

.brand {
  display: flex;
  align-items: center;
  flex-shrink: 0;
  text-decoration: none;
  color: inherit;
}
.brand-logo {
  height: 28px;
  width: auto;
  display: block;
}
/* 深色模式：单色藏青字标统一反白 */
[data-theme="dark"] .brand-logo { filter: brightness(0) invert(1); }

.topbar-right {
  display: flex;
  align-items: center;
  gap: 12px;
  flex: 1;
  justify-content: flex-end;
}

.search-wrap {
  position: relative;
  width: 100%;
  max-width: 420px;
}
.search-icon {
  position: absolute;
  left: 14px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--on-surface-variant);
  line-height: 0;
  pointer-events: none;
}
#search {
  width: 100%;
  padding: 11px 18px 11px 42px;
  border-radius: var(--radius-full);
  border: 1px solid var(--outline-variant);
  background: var(--surface-container-lowest);
  color: var(--on-surface);
  font-size: 14px;
  outline: none;
  transition: border-color var(--transition), box-shadow var(--transition);
}
#search:focus { border-color: var(--primary); box-shadow: 0 0 0 3px color-mix(in srgb, var(--primary) 20%, transparent); }

.ghost-btn {
  flex-shrink: 0;
  display: inline-flex;
  align-items: center;
  padding: 9px 18px;
  border: 1px solid var(--outline-variant);
  border-radius: var(--radius-full);
  background: transparent;
  color: var(--on-surface);
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: background-color var(--transition), border-color var(--transition);
}
.ghost-btn:hover { background: var(--surface-container-high); }

/* 主题切换按钮（首页 topbar：圆形图标按钮） */
.theme-toggle {
  flex-shrink: 0;
  width: 40px;
  height: 40px;
  border: 1px solid var(--outline-variant);
  border-radius: var(--radius-full);
  background: transparent;
  color: var(--on-surface);
  font-size: 18px;
  line-height: 1;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: background-color var(--transition), border-color var(--transition);
}
.theme-toggle:hover { background: var(--surface-container-high); }

/* 顶栏胶囊按钮（AI / Create） */
.pill-btn {
  flex-shrink: 0;
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 9px 16px;
  border: 1px solid var(--outline-variant);
  border-radius: var(--radius-full);
  background: transparent;
  color: var(--on-surface);
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  white-space: nowrap;
  transition: background-color var(--transition), border-color var(--transition), filter var(--transition);
}
.pill-btn:hover { background: var(--surface-container-high); }
.pill-btn .pill-label { line-height: 1; }
.pill-btn .pill-caret { margin-left: -2px; opacity: .65; }
.pill-primary {
  background: var(--primary);
  color: var(--on-primary);
  border-color: transparent;
}
.pill-primary:hover { background: var(--primary); filter: brightness(1.06); }

/* Create 下拉菜单 */
.create-wrap { position: relative; flex-shrink: 0; }
.create-menu {
  position: absolute;
  top: calc(100% + 10px);
  right: 0;
  width: 300px;
  padding: 8px;
  background: var(--surface-container-high);
  border: 1px solid var(--outline-variant);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  z-index: 60;
  animation: settings-pop 140ms ease-out;
  transform-origin: top right;
}
.cm-item {
  display: flex;
  align-items: center;
  gap: 12px;
  width: 100%;
  padding: 10px 12px;
  border: none;
  border-radius: var(--radius-md);
  background: transparent;
  color: var(--on-surface);
  text-align: left;
  text-decoration: none;
  cursor: pointer;
  transition: background-color var(--transition);
}
.cm-item:hover { background: var(--surface-container-highest); }
.cm-ic {
  flex: none;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  background: var(--primary-container);
  color: var(--on-primary-container);
}
.cm-text { display: flex; flex-direction: column; gap: 2px; min-width: 0; }
.cm-text b { font-size: 14px; font-weight: 600; }
.cm-text em { font-size: 12px; font-style: normal; color: var(--on-surface-variant); }

/* 分类 Tab（All / Learn / Explore / Play） */
.home-tabs {
  display: flex;
  gap: 6px;
  margin: 10px 4px 20px;
  flex-wrap: wrap;
}
.tab {
  padding: 7px 16px;
  border: none;
  border-radius: var(--radius-full);
  background: transparent;
  color: var(--on-surface-variant);
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: background-color var(--transition), color var(--transition);
}
.tab:hover { background: var(--surface-container-high); color: var(--on-surface); }
.tab.active { background: var(--on-surface); color: var(--surface); }
/* 拖动课程卡时：Tab 显出可放置边框；悬停的目标 Tab 高亮成「投放区」 */
body.sorting .home-tabs .tab { box-shadow: inset 0 0 0 1.5px var(--outline-variant); transition: none; }
.home-tabs .tab.drop-target {
  background: var(--primary);
  color: var(--on-primary);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--primary) 30%, transparent);
  transform: scale(1.06);
}

main {
  max-width: 1360px;
  margin: 0 auto;
  padding: 8px 40px 72px;
}

.section-title {
  font-size: 22px;
  font-weight: 600;
  color: var(--on-surface);
  letter-spacing: -0.01em;
  margin: 28px 4px 18px;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 18px;
}

/* NotebookLM 卡片 */
.nb-card {
  position: relative;
  display: flex;
  flex-direction: column;
  min-height: 188px;
  padding: 20px;
  border-radius: 20px;
  background: var(--surface-container);
  background: color-mix(in srgb, var(--accent, var(--primary)) 14%, var(--surface-container-lowest));
  border: 1px solid color-mix(in srgb, var(--accent, var(--primary)) 22%, transparent);
  color: var(--on-surface);
  overflow: hidden;
  transition: transform var(--transition), box-shadow var(--transition);
}
.nb-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-lg);
}

.nb-card-icon {
  font-family: "Apple Color Emoji", "Segoe UI Emoji", "Noto Color Emoji", "Segoe UI Symbol", sans-serif;
  font-size: 34px;
  line-height: 1;
  margin-bottom: auto;
}

.nb-card-body { margin-top: 16px; }

.nb-card-subject {
  display: inline-block;
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: color-mix(in srgb, var(--accent, var(--primary)) 78%, var(--on-surface));
  margin-bottom: 6px;
}

.nb-card-title {
  font-size: 18px;
  font-weight: 600;
  line-height: 1.35;
  margin: 0 0 6px;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.nb-card-meta {
  font-size: 13px;
  color: var(--on-surface-variant);
  margin: 0;
  line-height: 1.5;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.nb-progress {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-top: 12px;
  font-size: 12px;
  color: var(--on-surface-variant);
}
.nb-progress-bar {
  flex: 1;
  height: 4px;
  background: color-mix(in srgb, var(--on-surface) 14%, transparent);
  border-radius: var(--radius-full);
  overflow: hidden;
}
.nb-progress-bar > i {
  display: block;
  height: 100%;
  background: var(--accent, var(--primary));
  border-radius: var(--radius-full);
}

.empty-state {
  padding: 48px 0;
  text-align: center;
  color: var(--on-surface-variant);
  font-size: 14px;
}

/* 区段标题行（标题 + 创建按钮） */
.section-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin: 28px 4px 18px;
}
.section-head .section-title { margin: 0; }

.create-btn {
  flex-shrink: 0;
  padding: 9px 18px;
  border: none;
  border-radius: var(--radius-full);
  background: var(--primary-container);
  color: var(--on-primary-container);
  font-size: 14px;
  font-weight: 600;
  transition: filter var(--transition), box-shadow var(--transition);
}
.create-btn:hover { filter: brightness(0.97); box-shadow: var(--shadow-sm); }

/* 卡片上的删除按钮（仅动态课程，hover 显示） */
.nb-del {
  position: absolute;
  top: 10px;
  right: 10px;
  width: 28px;
  height: 28px;
  border: none;
  border-radius: var(--radius-full);
  background: color-mix(in srgb, var(--on-surface) 9%, transparent);
  color: var(--on-surface-variant);
  font-size: 13px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  z-index: 2;
  transition: opacity var(--transition), background-color var(--transition), color var(--transition);
}
.nb-card:hover .nb-del { opacity: 1; }
.nb-del:hover { background: var(--error); color: var(--on-error); }
/* 有拖拽手柄时，删除键给手柄让位（手柄占最右上角） */
.nb-card:has(.nb-drag) .nb-del { right: 46px; }

/* 卡片上的编辑按钮（仅站内可编辑的 Markdown 课程，hover 显示） */
.nb-edit {
  position: absolute;
  top: 10px;
  right: 46px;
  width: 28px;
  height: 28px;
  border: none;
  border-radius: var(--radius-full);
  background: color-mix(in srgb, var(--on-surface) 9%, transparent);
  color: var(--on-surface-variant);
  font-size: 13px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  z-index: 2;
  transition: opacity var(--transition), background-color var(--transition), color var(--transition);
}
.nb-card:hover .nb-edit { opacity: 1; }
.nb-edit:hover { background: var(--primary); color: var(--on-primary); }
/* 有拖拽手柄时：手柄占最右，删除让位 46px，编辑再让 36px */
.nb-card:has(.nb-drag) .nb-edit { right: 82px; }

/* 拖拽排序手柄（主网格卡片右上角） */
.nb-drag {
  position: absolute;
  top: 10px;
  right: 10px;
  width: 28px;
  height: 28px;
  border: none;
  border-radius: var(--radius-full);
  background: color-mix(in srgb, var(--on-surface) 9%, transparent);
  color: var(--on-surface-variant);
  font-size: 14px;
  line-height: 1;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: grab;
  opacity: 0;
  z-index: 2;
  touch-action: none;          /* 触屏：手柄上不滚动页面，交给拖拽 */
  transition: opacity var(--transition), background-color var(--transition);
}
.nb-card:hover .nb-drag { opacity: 1; }
.nb-drag:hover { background: var(--surface-container-highest); color: var(--on-surface); }
.nb-drag:active { cursor: grabbing; }

/* 拖拽中：被拖卡片留下的占位 + 跟随指针的浮层 */
.nb-card-placeholder {
  opacity: .28;
  filter: grayscale(.3);
}
.nb-card-ghost {
  box-shadow: var(--shadow-lg);
  transform: scale(1.04) rotate(1.5deg);
  opacity: .96;
  cursor: grabbing;
}
.nb-card-ghost .nb-drag,
.nb-card-ghost .nb-del { display: none; }
body.sorting { user-select: none; cursor: grabbing; }
body.sorting .nb-card { transition: none; }
body.sorting .nb-card:hover { transform: none; box-shadow: none; }

/* 创建课程弹窗 */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.45);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
  padding: 20px;
  animation: fadeIn 150ms ease-out;
}
.modal {
  background: var(--surface-container-high);
  border-radius: var(--radius-lg);
  padding: 24px;
  width: 440px;
  max-width: 100%;
  box-shadow: var(--shadow-lg);
}
.modal h3 { font-size: 18px; margin-bottom: 18px; }

.field { display: block; margin-bottom: 14px; }
.field > span {
  display: block;
  font-size: 12px;
  font-weight: 500;
  color: var(--on-surface-variant);
  margin-bottom: 6px;
}
.field > span em { color: var(--error); font-style: normal; }
.field input[type="text"] {
  width: 100%;
  padding: 11px 14px;
  border: 1px solid var(--outline);
  border-radius: var(--radius-sm);
  background: var(--surface-container-lowest);
  color: var(--on-surface);
  font-size: 14px;
  outline: none;
  transition: border-color var(--transition);
}
.field input[type="text"]:focus { border-color: var(--primary); }
.field input[type="file"] { width: 100%; font-size: 13px; color: var(--on-surface-variant); }
.field input[type="file"]::file-selector-button {
  margin-right: 10px;
  padding: 8px 14px;
  border: 1px solid var(--outline-variant);
  border-radius: var(--radius-full);
  background: var(--surface-container);
  color: var(--on-surface);
  font-size: 13px;
  cursor: pointer;
}
.field-row { display: flex; gap: 12px; }
.field-row .field { flex: 1; }
/* 上传弹窗：AI 智能填充按钮 + 标签 chips + 图标点选网格 */
.ai-fill-row { display: flex; align-items: center; gap: 10px; margin: -4px 0 16px; }
.ai-fill-btn {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  border: 1px solid var(--primary);
  color: var(--primary);
  background: transparent;
  border-radius: 999px;
  padding: 6px 14px;
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: background .15s, color .15s;
  white-space: nowrap;
}
.ai-fill-btn:hover:not(:disabled) { background: var(--primary); color: var(--on-primary); }
.ai-fill-btn:disabled { opacity: .55; cursor: progress; }
.ai-fill-status { font-size: 12px; color: var(--on-surface-variant); }
.ai-fill-status.err { color: var(--error); }

.tag-chips { display: flex; flex-wrap: wrap; gap: 6px; min-height: 28px; align-items: center; }
.tag-chip {
  display: inline-flex; align-items: center; gap: 4px;
  background: var(--surface-container-highest);
  color: var(--on-surface);
  border-radius: 999px;
  padding: 3px 6px 3px 10px;
  font-size: 12px;
}
.tag-chip button { border: 0; background: none; color: var(--on-surface-variant); cursor: pointer; font-size: 14px; line-height: 1; padding: 0; }
.tag-chip button:hover { color: var(--error); }
.tag-empty { font-size: 12px; color: var(--on-surface-variant); }

.icon-picker {
  display: flex; flex-wrap: wrap; gap: 6px;
  max-height: 124px; overflow-y: auto;
  padding: 8px;
  border: 1px solid var(--outline, rgba(0,0,0,.12));
  border-radius: 12px;
  background: var(--surface-container, rgba(0,0,0,.02));
}
.icon-opt {
  width: 34px; height: 34px;
  display: flex; align-items: center; justify-content: center;
  /* 显式走彩色 emoji 字体：部分系统下 button 不会自动回退到 emoji 字体，会显示空白方块 */
  font-family: "Apple Color Emoji", "Segoe UI Emoji", "Noto Color Emoji", "Segoe UI Symbol", sans-serif;
  font-size: 19px; line-height: 1;
  border: 1.5px solid transparent;
  border-radius: 9px;
  background: transparent;
  cursor: pointer;
  transition: background .12s, border-color .12s;
}
.icon-opt:hover { background: var(--surface-container-highest); }
.icon-opt.selected { border-color: var(--primary); background: color-mix(in srgb, var(--primary) 14%, transparent); }

.modal-hint { font-size: 12px; color: var(--on-surface-variant); margin: 4px 0 18px; }
.modal-hint.err { color: var(--error); }

.modal .btn-row { display: flex; gap: 8px; justify-content: flex-end; }
.modal .btn-row button {
  padding: 9px 22px;
  border: none;
  border-radius: var(--radius-full);
  font-size: 14px;
  font-weight: 500;
  transition: background-color var(--transition), filter var(--transition);
}
.modal .btn-cancel { background: transparent; color: var(--on-surface); }
.modal .btn-cancel:hover { background: var(--surface-container-highest); }
.modal .btn-confirm { background: var(--primary); color: var(--on-primary); }
.modal .btn-confirm:hover:not(:disabled) { filter: brightness(1.05); }
.modal .btn-confirm:disabled { opacity: 0.6; cursor: not-allowed; }

/* ========================================
   阅读器（全屏 + 悬浮工具栏）
   ======================================== */
body.reader {
  height: 100vh;
  overflow: hidden;
  background: var(--surface);
}

#content {
  position: fixed;
  inset: 0;
  width: 100%;
  height: 100%;
  border: none;
  background: var(--surface);
}

/* 顶部感应区：鼠标移上去唤出工具栏 */
.reader-hotzone {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: 12px;
  z-index: 9;
}

.reader-bar {
  position: fixed;
  top: 12px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  align-items: center;
  gap: 8px;
  max-width: calc(100vw - 24px);
  padding: 7px 10px 7px 8px;
  border-radius: var(--radius-full);
  background: color-mix(in srgb, var(--surface-container) 86%, transparent);
  -webkit-backdrop-filter: blur(14px) saturate(1.4);
  backdrop-filter: blur(14px) saturate(1.4);
  border: 1px solid var(--outline-variant);
  box-shadow: var(--shadow-md);
  z-index: 11;
  transition: transform 250ms cubic-bezier(0.2,0,0,1), opacity 250ms ease;
}
.reader-bar.hidden {
  transform: translateX(-50%) translateY(-150%);
  opacity: 0;
  pointer-events: none;
}

.rb-btn {
  width: 38px;
  height: 38px;
  flex-shrink: 0;
  border: none;
  background: transparent;
  color: var(--on-surface);
  border-radius: var(--radius-full);
  font-size: 18px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: background-color var(--transition);
}
.rb-btn:hover { background: var(--surface-container-highest); }
.rb-back { font-size: 20px; }

/* 工具栏设为「隐藏」时的最小化返回键：始终悬浮在左上角、半透明不挡正文，
   保证没有浏览器返回手势/按钮的人也能退出课程。hover 变实。 */
.reader-mini-back {
  position: fixed;
  top: 12px;
  left: 12px;
  width: 40px;
  height: 40px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: var(--on-surface);
  border-radius: var(--radius-full);
  background: color-mix(in srgb, var(--surface-container) 80%, transparent);
  -webkit-backdrop-filter: blur(14px) saturate(1.4);
  backdrop-filter: blur(14px) saturate(1.4);
  border: 1px solid var(--outline-variant);
  box-shadow: var(--shadow-md);
  text-decoration: none;
  opacity: 0.55;
  transition: opacity 200ms ease, background 200ms ease;
  z-index: 11;
}
.reader-mini-back:hover { opacity: 1; background: var(--surface-container-highest); }
.reader-mini-back[hidden] { display: none; }

.rb-info {
  display: flex;
  align-items: center;
  gap: 8px;
  min-width: 0;
  padding: 0 6px;
}
.rb-subject {
  flex-shrink: 0;
  padding: 3px 10px;
  border-radius: var(--radius-full);
  background: var(--primary-container);
  color: var(--on-primary-container);
  font-size: 11px;
  font-weight: 600;
}
.rb-title {
  font-size: 14px;
  font-weight: 500;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  max-width: 38vw;
}

.rb-progress {
  flex-shrink: 0;
  padding: 0 8px;
  font-size: 12px;
  color: var(--on-surface-variant);
  font-variant-numeric: tabular-nums;
}

/* 阅读工具栏：Aa 按钮（文字款） */
.rb-aa { font-size: 14px; font-weight: 700; letter-spacing: 0.02em; }

/* 只读分享徽标（仅分享模式显示） */
.rb-ro {
  flex-shrink: 0;
  font-size: 11px;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: var(--radius-full);
  background: var(--primary-container);
  color: var(--on-primary-container);
}

/* 分享模式：隐藏一切「回主页 / 写入账号」的入口，只保留纯阅读功能 */
body.share-mode .rb-back,
body.share-mode #chat-toggle,
body.share-mode #bookmark-btn,
body.share-mode #bookmarks-toggle,
body.share-mode #share-btn { display: none; }

/* 分享对话框 */
.share-exp { flex-wrap: wrap; }
.share-exp .seg-btn { flex: 1 0 auto; min-width: 54px; }
.share-result { margin: 4px 0 14px; }
.share-link-row { display: flex; gap: 8px; align-items: stretch; }
.share-link-row input {
  flex: 1; min-width: 0;
  border: 1px solid var(--outline-variant);
  border-radius: 10px;
  background: var(--surface-container-lowest);
  color: var(--on-surface);
  font-size: 12.5px;
  padding: 9px 12px;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}
.share-link-row .btn-confirm {
  flex: none;
  border: none;
  cursor: pointer;
  font-size: 13px;
  font-weight: 600;
  padding: 9px 18px;
  border-radius: 10px;
}

/* 更多菜单（工具栏右端 ⋯ 下拉） */
.more-menu {
  position: fixed;
  top: 64px;
  right: 16px;
  width: 230px;
  padding: 8px;
  background: var(--surface-container-high);
  border: 1px solid var(--outline-variant);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  z-index: 14;
  animation: settings-pop 140ms ease-out;
  transform-origin: top right;
}
.mm-item {
  display: flex;
  align-items: center;
  gap: 10px;
  width: 100%;
  padding: 10px 10px;
  border: none;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--on-surface);
  font-size: 13.5px;
  text-align: left;
  cursor: pointer;
  transition: background-color var(--transition);
}
.mm-item:hover { background: var(--surface-container-highest); }
.mm-item .mm-ic { width: 20px; text-align: center; font-size: 15px; flex: none; }
.mm-item .mm-state { margin-left: auto; color: var(--primary); font-weight: 700; }
.mm-divider { height: 1px; background: var(--outline-variant); margin: 6px 4px; }

/* 阅读设置面板 */
#prefs-panel {
  position: fixed;
  top: 64px;
  right: 16px;
  width: 320px;
  background: var(--surface-container);
  border: 1px solid var(--outline-variant);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  z-index: 13;
  overflow: hidden;
}
.prefs-body { padding: 14px 16px 16px; display: flex; flex-direction: column; gap: 14px; }
.pref-row { display: flex; align-items: center; gap: 12px; }
.pref-label { flex: none; width: 58px; font-size: 12.5px; font-weight: 600; color: var(--on-surface-variant); }
.pref-row .seg { flex: 1; }
.pref-val {
  flex: none; width: 44px; text-align: right;
  font-size: 12px; color: var(--on-surface-variant); font-variant-numeric: tabular-nums;
}
#pref-scale { flex: 1; accent-color: var(--primary); }
.pref-reset {
  align-self: flex-start;
  padding: 7px 16px;
  border: 1px solid var(--outline-variant);
  border-radius: var(--radius-full);
  background: transparent;
  color: var(--on-surface);
  font-size: 12.5px;
  transition: background-color var(--transition);
}
.pref-reset:hover { background: var(--surface-container-highest); }
#prefs-panel .sm-tip { margin: 0; }

/* 分屏对话：正文让出右侧，对话面板贴边成柱 */
body.reader.split-chat #content { width: calc(100% - min(420px, 44vw)); }
body.reader.split-chat #chat-panel {
  top: 0;
  right: 0;
  bottom: 0;
  width: min(420px, 44vw);
  max-width: none;
  max-height: none;
  height: 100vh;
  border-radius: 0;
  border: none;
  border-left: 1px solid var(--outline-variant);
  box-shadow: none;
}

/* 轻提示 toast */
#nb-toast {
  position: fixed;
  bottom: 28px;
  left: 50%;
  transform: translateX(-50%) translateY(12px);
  padding: 10px 20px;
  background: var(--surface-container-highest);
  color: var(--on-surface);
  border: 1px solid var(--outline-variant);
  border-radius: var(--radius-full);
  box-shadow: var(--shadow-lg);
  font-size: 13px;
  opacity: 0;
  pointer-events: none;
  z-index: 300;
  transition: opacity 200ms ease, transform 200ms ease;
}
#nb-toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }

/* 书签面板 */
#bookmarks-panel {
  position: fixed;
  top: 64px;
  right: 16px;
  width: 320px;
  max-height: calc(100vh - 80px);
  display: flex;
  flex-direction: column;
  background: var(--surface-container);
  border: 1px solid var(--outline-variant);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  z-index: 12;
  overflow: hidden;
}
.panel-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 16px;
  border-bottom: 1px solid var(--outline-variant);
}
.panel-header h3 { display: flex; align-items: center; gap: 7px; font-size: 14px; font-weight: 600; }
.panel-header h3 .chat-status { font-weight: 400; }
.ph-actions { display: flex; align-items: center; gap: 2px; }

/* AI 模型切换条：独占一行，custom 样式的下拉 + 圆角胶囊 */
.chat-model-bar {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  border-bottom: 1px solid var(--outline-variant);
  background: var(--surface-container-low);
}
.chat-model-bar .cmb-icon { display: inline-flex; color: var(--on-surface-variant); }
.chat-model-bar .cmb-label {
  font-size: 12px;
  color: var(--on-surface-variant);
  white-space: nowrap;
}
.cmb-select { position: relative; flex: 1; min-width: 0; }
.cmb-select select {
  width: 100%;
  appearance: none;
  -webkit-appearance: none;
  font-size: 12.5px;
  line-height: 1.4;
  padding: 6px 30px 6px 12px;
  background: var(--surface-container-high);
  color: var(--on-surface);
  border: 1px solid var(--outline-variant);
  border-radius: var(--radius-full);
  cursor: pointer;
  text-overflow: ellipsis;
  transition: border-color var(--transition), background-color var(--transition), box-shadow var(--transition);
}
.cmb-select select:hover { background: var(--surface-container-highest); }
.cmb-select select:focus-visible {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--primary) 20%, transparent);
}
.cmb-select .cmb-caret {
  position: absolute;
  right: 11px;
  top: 50%;
  transform: translateY(-50%);
  pointer-events: none;
  line-height: 0;
  color: var(--on-surface-variant);
}
#bookmarks-list {
  list-style: none;
  padding: 8px;
  margin: 0;
  overflow-y: auto;
  flex: 1;
}
#bookmarks-list li {
  display: flex;
  align-items: center;
  gap: 4px;
  border-radius: var(--radius-sm);
  transition: background-color var(--transition);
}
#bookmarks-list li:hover { background: var(--surface-container-high); }
#bookmarks-list .bm-jump {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 2px;
  align-items: flex-start;
  text-align: left;
  padding: 10px 12px;
  border: none;
  background: transparent;
  color: var(--on-surface);
  font-size: 13px;
  border-radius: var(--radius-sm);
}
#bookmarks-list .bm-jump .bm-pct {
  font-size: 11px;
  color: var(--on-surface-variant);
  font-variant-numeric: tabular-nums;
}
#bookmarks-list .bm-del {
  width: 32px;
  height: 32px;
  margin-right: 4px;
  border: none;
  background: transparent;
  color: var(--on-surface-variant);
  border-radius: var(--radius-full);
  font-size: 14px;
  opacity: 0;
  transition: opacity var(--transition), background-color var(--transition);
}
#bookmarks-list li:hover .bm-del { opacity: 1; }
#bookmarks-list .bm-del:hover { background: var(--surface-container-highest); color: var(--error); }
.empty-hint {
  padding: 32px 16px;
  text-align: center;
  font-size: 13px;
  color: var(--on-surface-variant);
  margin: 0;
}

/* ========================================
   目录 TOC 面板（左侧，镜像书签面板）
   ======================================== */
#toc-panel {
  position: fixed;
  top: 64px;
  left: 16px;
  width: 300px;
  max-height: calc(100vh - 80px);
  display: flex;
  flex-direction: column;
  background: var(--surface-container);
  border: 1px solid var(--outline-variant);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  z-index: 12;
  overflow: hidden;
}
#toc-list { list-style: none; padding: 8px; margin: 0; overflow-y: auto; flex: 1; }
#toc-list li { margin: 0; }
.toc-item {
  display: block;
  width: 100%;
  text-align: left;
  padding: 7px 12px;
  border: none;
  background: transparent;
  color: var(--on-surface);
  font-size: 13px;
  line-height: 1.4;
  border-radius: var(--radius-sm);
  cursor: pointer;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  transition: background-color var(--transition);
}
.toc-item:hover { background: var(--surface-container-high); }
.toc-item:disabled { opacity: .5; cursor: default; }
.toc-item.lvl-0 { font-weight: 600; }
.toc-item.lvl-1 { padding-left: 26px; }
.toc-item.lvl-2 { padding-left: 40px; color: var(--on-surface-variant); }

/* ========================================
   AI 对话面板（RAG）
   ======================================== */
#chat-panel {
  position: fixed;
  top: 64px;
  right: 16px;
  width: 380px;
  max-width: calc(100vw - 32px);
  max-height: calc(100vh - 80px);
  display: flex;
  flex-direction: column;
  background: var(--surface-container);
  border: 1px solid var(--outline-variant);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  z-index: 13;
  overflow: hidden;
}
.chat-status { font-size: 11px; font-weight: 400; color: var(--on-surface-variant); margin-left: 6px; }
.chat-msgs {
  flex: 1;
  overflow-y: auto;
  padding: 14px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.chat-hint { font-size: 12.5px; line-height: 1.6; color: var(--on-surface-variant); margin: 4px 2px; }
.chat-msg { display: flex; flex-direction: column; gap: 6px; max-width: 100%; }
.chat-msg.user { align-items: flex-end; }
.chat-msg.ai { align-items: flex-start; }
.chat-bubble {
  padding: 9px 12px;
  border-radius: 14px;
  font-size: 13.5px;
  line-height: 1.62;
  white-space: pre-wrap;
  word-break: break-word;
  max-width: 90%;
}
.chat-msg.user .chat-bubble { background: var(--primary); color: var(--on-primary); border-bottom-right-radius: 4px; }
.chat-msg.ai .chat-bubble { background: var(--surface-container-high); color: var(--on-surface); border-bottom-left-radius: 4px; }
.chat-msg.thinking .chat-bubble { color: var(--on-surface-variant); animation: chat-pulse 1.1s ease-in-out infinite; }
@keyframes chat-pulse { 0%,100% { opacity: .5; } 50% { opacity: 1; } }

/* AI 回答的 Markdown 渲染 */
.chat-bubble.md { white-space: normal; }
.chat-bubble.md > :first-child { margin-top: 0; }
.chat-bubble.md > :last-child { margin-bottom: 0; }
.chat-bubble.md p { margin: 0 0 8px; }
.chat-bubble.md ul, .chat-bubble.md ol { margin: 4px 0 8px; padding-left: 20px; }
.chat-bubble.md li { margin: 2px 0; }
.chat-bubble.md h4 { font-size: 15px; font-weight: 600; margin: 10px 0 6px; }
.chat-bubble.md h5 { font-size: 13.5px; font-weight: 600; margin: 8px 0 4px; }
.chat-bubble.md code {
  background: color-mix(in srgb, var(--on-surface) 12%, transparent);
  padding: 1px 5px;
  border-radius: 5px;
  font-size: .92em;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}
.chat-bubble.md pre {
  background: var(--surface-container-lowest);
  border: 1px solid var(--outline-variant);
  border-radius: 8px;
  padding: 10px 12px;
  overflow-x: auto;
  margin: 6px 0;
}
.chat-bubble.md pre code { background: none; padding: 0; }
.chat-bubble.md a { color: var(--primary); text-decoration: underline; }
.chat-bubble.md blockquote {
  margin: 6px 0;
  padding: 2px 10px;
  border-left: 3px solid var(--outline-variant);
  color: var(--on-surface-variant);
}
.chat-bubble.md hr { border: none; border-top: 1px solid var(--outline-variant); margin: 8px 0; }
.chat-sources { display: flex; flex-wrap: wrap; align-items: center; gap: 6px; padding-left: 2px; }
.cs-label { font-size: 11px; color: var(--on-surface-variant); }
.cs-chip {
  border: 1px solid var(--outline-variant);
  background: var(--surface-container-high);
  color: var(--primary);
  border-radius: 999px;
  padding: 3px 10px;
  font-size: 11.5px;
  cursor: pointer;
  max-width: 100%;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  transition: background-color var(--transition);
}
.cs-chip:hover { background: var(--surface-container-highest); }
.chat-quote {
  display: flex; align-items: center; gap: 8px;
  margin: 0 12px;
  padding: 7px 10px;
  background: var(--surface-container-high);
  border-left: 3px solid var(--primary);
  border-radius: 8px;
  font-size: 12px;
}
.cq-label { color: var(--primary); font-weight: 600; flex: none; }
.cq-text { color: var(--on-surface-variant); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; flex: 1; }
.cq-clear { border: none; background: none; color: var(--on-surface-variant); cursor: pointer; font-size: 13px; flex: none; }
.cq-clear:hover { color: var(--error); }
.chat-form {
  display: flex; align-items: flex-end; gap: 8px;
  padding: 10px 12px;
  border-top: 1px solid var(--outline-variant);
}
#chat-input, #omni-input {
  flex: 1;
  resize: none;
  border: 1px solid var(--outline-variant);
  border-radius: 12px;
  padding: 9px 12px;
  font: inherit;
  font-size: 13.5px;
  line-height: 1.5;
  background: var(--surface-container-lowest, var(--surface-container));
  color: var(--on-surface);
  max-height: 120px;
}
#chat-input:focus, #omni-input:focus { outline: none; border-color: var(--primary); }
#chat-send, #omni-send {
  flex: none;
  width: 38px; height: 38px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: none;
  border-radius: 50%;
  background: var(--primary);
  color: var(--on-primary);
  cursor: pointer;
  transition: filter var(--transition);
}
#chat-send:hover, #omni-send:hover { filter: brightness(1.06); }
@media (max-width: 640px) {
  #chat-panel { right: 8px; left: 8px; width: auto; }
}

/* 首页「全能问答」面板：复用课程内对话的 .chat-* 内部样式，仅定位不同 */
#omni-panel {
  position: fixed;
  top: 84px;
  right: 24px;
  width: 400px;
  max-width: calc(100vw - 32px);
  max-height: calc(100vh - 104px);
  display: flex;
  flex-direction: column;
  background: var(--surface-container);
  border: 1px solid var(--outline-variant);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  z-index: 90;
  overflow: hidden;
  animation: settings-pop 160ms ease-out;
  transform-origin: top right;
}
.sh-actions { display: flex; align-items: center; gap: 10px; }
.omni-btn { padding: 9px 16px; }
@media (max-width: 640px) {
  #omni-panel { right: 8px; left: 8px; width: auto; top: 72px; }
}

/* 划词浮条里的「问 AI」按钮 */
.nb-hl-sep { width: 1px; align-self: stretch; margin: 4px 2px; background: rgba(255,255,255,.25); }
.nb-hl-ask {
  border: none; background: transparent; cursor: pointer;
  font-size: 15px; line-height: 1; padding: 0 4px;
  display: inline-flex; align-items: center; justify-content: center;
}

/* ========================================
   高亮：选区浮条 + 批注弹层（建在父页）
   ======================================== */
.nb-hl-toolbar {
  position: fixed;
  z-index: 50;
  transform: translate(-50%, -100%);
  display: none;
  gap: 6px;
  padding: 6px 8px;
  background: var(--surface-container-high);
  border: 1px solid var(--outline-variant);
  border-radius: var(--radius-full);
  box-shadow: var(--shadow-lg);
}
.nb-hl-toolbar[data-below="1"] { transform: translate(-50%, 0); }
.nb-hl-toolbar.show { display: flex; }
.nb-hl-swatch {
  width: 22px;
  height: 22px;
  border-radius: 50%;
  border: 1px solid rgba(0, 0, 0, .15);
  cursor: pointer;
  padding: 0;
  transition: transform var(--transition);
}
.nb-hl-swatch:hover { transform: scale(1.14); }

.nb-hl-popover {
  position: fixed;
  z-index: 50;
  width: 240px;
  transform: translateY(-100%);
  display: none;
  flex-direction: column;
  gap: 10px;
  padding: 12px;
  background: var(--surface-container-high);
  border: 1px solid var(--outline-variant);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
}
.nb-hl-popover[data-below="1"] { transform: translateY(0); }
.nb-hl-popover.show { display: flex; }
.nb-hl-colors { display: flex; gap: 8px; }
.nb-hl-note {
  width: 100%;
  resize: vertical;
  border: 1px solid var(--outline);
  border-radius: var(--radius-sm);
  background: var(--surface-container-lowest);
  color: var(--on-surface);
  font: inherit;
  font-size: 13px;
  padding: 8px;
  outline: none;
}
.nb-hl-note:focus { border-color: var(--primary); }
.nb-hl-actions { display: flex; justify-content: space-between; }
.nb-hl-actions button {
  padding: 6px 14px;
  border: none;
  border-radius: var(--radius-full);
  font-size: 13px;
  cursor: pointer;
}
.nb-hl-del { background: transparent; color: var(--error); }
.nb-hl-del:hover { background: color-mix(in srgb, var(--error) 16%, transparent); }
.nb-hl-done { background: var(--primary); color: var(--on-primary); }

/* 加书签弹框 */
.bm-prompt-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.4);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
  animation: fadeIn 150ms ease-out;
}
.bm-prompt {
  background: var(--surface-container-high);
  border-radius: var(--radius-lg);
  padding: 24px;
  width: 360px;
  max-width: calc(100vw - 32px);
  box-shadow: var(--shadow-lg);
}
.bm-prompt h3 { font-size: 16px; margin-bottom: 16px; }
.bm-prompt input {
  width: 100%;
  padding: 12px 16px;
  border: 1px solid var(--outline);
  border-radius: var(--radius-sm);
  background: var(--surface-container-lowest);
  color: var(--on-surface);
  font-size: 14px;
  outline: none;
  margin-bottom: 16px;
}
.bm-prompt input:focus { border-color: var(--primary); }
.bm-prompt .btn-row { display: flex; gap: 8px; justify-content: flex-end; }
.bm-prompt button {
  padding: 8px 20px;
  border: none;
  border-radius: var(--radius-full);
  font-size: 13px;
  font-weight: 500;
  transition: background-color var(--transition);
}
.bm-prompt .btn-cancel { background: transparent; color: var(--on-surface); }
.bm-prompt .btn-cancel:hover { background: var(--surface-container-highest); }
.bm-prompt .btn-confirm { background: var(--primary); color: var(--on-primary); }
.bm-prompt .btn-confirm:hover { filter: brightness(0.95); }

@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }

/* ========================================
   深入搜索弹窗（首页搜索框按 Enter 打开）
   ======================================== */
.search-modal {
  width: 640px;
  max-width: calc(100vw - 32px);
  max-height: min(640px, calc(100vh - 64px));
  display: flex;
  flex-direction: column;
  padding: 0;
  overflow: hidden;
}
.srch-head {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 16px 18px 12px;
  border-bottom: 1px solid var(--outline-variant);
}
.srch-head h3 { font-size: 16px; margin: 0; flex: none; }
.srch-q {
  flex: 1;
  min-width: 0;
  font-size: 13px;
  color: var(--on-surface-variant);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.srch-body { overflow-y: auto; padding: 12px 14px 18px; }
.srch-section-title {
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--on-surface-variant);
  margin: 12px 6px 8px;
}
.srch-item {
  display: block;
  width: 100%;
  text-align: left;
  padding: 10px 12px;
  border: 1px solid transparent;
  border-radius: var(--radius-md);
  background: transparent;
  color: var(--on-surface);
  cursor: pointer;
  transition: background-color var(--transition);
}
.srch-item:hover { background: var(--surface-container-high); }
.srch-item-top { display: flex; align-items: center; gap: 8px; margin-bottom: 4px; }
.srch-item-course { font-size: 13.5px; font-weight: 600; }
.srch-item-heading {
  font-size: 11px;
  padding: 2px 9px;
  border-radius: var(--radius-full);
  background: var(--primary-container);
  color: var(--on-primary-container);
  max-width: 50%;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.srch-item-count { margin-left: auto; font-size: 11px; color: var(--on-surface-variant); flex: none; }
.srch-item-text {
  font-size: 12.5px;
  line-height: 1.6;
  color: var(--on-surface-variant);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.srch-item-text mark {
  background: color-mix(in srgb, var(--primary) 26%, transparent);
  color: inherit;
  border-radius: 3px;
  padding: 0 1px;
}
.srch-empty, .srch-loading {
  padding: 36px 16px;
  text-align: center;
  font-size: 13px;
  color: var(--on-surface-variant);
}
.srch-foot-tip {
  margin: 14px 6px 0;
  font-size: 11.5px;
  line-height: 1.6;
  color: var(--on-surface-variant);
}

/* ========================================
   登录页
   ======================================== */
body.login {
  min-height: 100vh;
  display: grid;
  place-items: center;
  background:
    radial-gradient(at 20% 30%, var(--primary-container) 0%, transparent 50%),
    radial-gradient(at 80% 70%, var(--tertiary-container) 0%, transparent 50%),
    var(--surface);
  padding: 24px;
}
.login-card {
  background: var(--surface-container);
  border-radius: var(--radius-xl);
  padding: 48px 40px;
  width: 100%;
  max-width: 400px;
  box-shadow: var(--shadow-md);
}
.login-logo {
  width: 210px;
  max-width: 72%;
  height: auto;
  display: block;
  margin: 4px auto 22px;
}
[data-theme="dark"] .login-logo { filter: brightness(0) invert(1); }
body.login .eyebrow { display: block; text-align: center; margin: 0 0 26px; }
.login-card label {
  display: block;
  font-size: 12px;
  font-weight: 500;
  color: var(--on-surface-variant);
  margin-bottom: 8px;
}
#password {
  width: 100%;
  padding: 16px 20px;
  border: 1px solid var(--outline);
  border-radius: var(--radius-sm);
  background: var(--surface-container-lowest);
  color: var(--on-surface);
  font-size: 16px;
  outline: none;
  margin-bottom: 24px;
  transition: border-color var(--transition);
}
#password:focus { border-color: var(--primary); border-width: 2px; padding: 15px 19px; }
#submit-btn {
  width: 100%;
  padding: 14px;
  border: none;
  border-radius: var(--radius-full);
  background: var(--primary);
  color: var(--on-primary);
  font-size: 15px;
  font-weight: 500;
  transition: filter var(--transition);
}
#submit-btn:hover:not(:disabled) { filter: brightness(1.05); }
#submit-btn:disabled { opacity: 0.6; cursor: not-allowed; }
.error-msg {
  margin-top: 16px;
  padding: 12px 16px;
  background: var(--error);
  color: var(--on-error);
  border-radius: var(--radius-sm);
  font-size: 13px;
  text-align: center;
}

/* ========================================
   响应式
   ======================================== */
@media (max-width: 640px) {
  .topbar { padding: 16px 20px; flex-wrap: wrap; gap: 14px; }
  .topbar-right { width: 100%; }
  .search-wrap { max-width: none; flex: 1; }
  /* 窄屏胶囊收成纯图标，省横向空间 */
  .pill-btn .pill-label, .pill-btn .pill-caret { display: none; }
  .pill-btn { padding: 9px 11px; }
  .create-menu { width: min(300px, calc(100vw - 40px)); }
  main { padding: 8px 20px 56px; }
  .card-grid { grid-template-columns: 1fr 1fr; gap: 12px; }
  .nb-card { min-height: 160px; padding: 16px; }
  .rb-title { max-width: 44vw; }
  #bookmarks-panel { right: 8px; left: 8px; width: auto; }
  #toc-panel { left: 8px; right: 8px; width: auto; }
  #prefs-panel { right: 8px; left: 8px; width: auto; }
  /* 窄屏分屏没有意义，退回浮层布局 */
  body.reader.split-chat #content { width: 100%; }
  body.reader.split-chat #chat-panel {
    top: 64px; right: 8px; left: 8px; bottom: auto;
    width: auto; height: auto; max-height: calc(100vh - 80px);
    border: 1px solid var(--outline-variant); border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
  }
}
@media (max-width: 400px) {
  .card-grid { grid-template-columns: 1fr; }
}

/* ========================================
   设置下拉（⚙️ 外观 / 关于 / 退出）
   ======================================== */
.settings-wrap { position: relative; flex-shrink: 0; }
.settings-btn {
  width: 40px;
  height: 40px;
  border: 1px solid var(--outline-variant);
  border-radius: var(--radius-full);
  background: transparent;
  color: var(--on-surface);
  font-size: 18px;
  line-height: 1;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: background-color var(--transition), border-color var(--transition), transform var(--transition);
}
.settings-btn:hover { background: var(--surface-container-high); }
.settings-btn[aria-expanded="true"] { background: var(--surface-container-high); transform: rotate(45deg); }

.settings-menu {
  position: absolute;
  top: calc(100% + 10px);
  right: 0;
  width: 248px;
  padding: 10px;
  background: var(--surface-container-high);
  border: 1px solid var(--outline-variant);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  z-index: 60;
  animation: settings-pop 140ms ease-out;
  transform-origin: top right;
}
@keyframes settings-pop {
  from { opacity: 0; transform: translateY(-6px) scale(0.97); }
  to   { opacity: 1; transform: translateY(0) scale(1); }
}
.sm-section { padding: 6px 6px 10px; }
.sm-label {
  display: block;
  font-size: 11px;
  font-weight: 600;
  letter-spacing: .04em;
  text-transform: uppercase;
  color: var(--on-surface-variant);
  margin-bottom: 8px;
}
.seg {
  display: flex;
  gap: 4px;
  padding: 4px;
  background: var(--surface-container-lowest);
  border-radius: var(--radius-full);
}
.seg-btn {
  flex: 1;
  padding: 7px 4px;
  border: none;
  border-radius: var(--radius-full);
  background: transparent;
  color: var(--on-surface-variant);
  font-size: 12px;
  font-weight: 500;
  white-space: nowrap;
  cursor: pointer;
  transition: background-color var(--transition), color var(--transition);
}
.seg-btn:hover { color: var(--on-surface); }
.seg-btn.active {
  background: var(--primary);
  color: #fff;
  box-shadow: var(--shadow-sm, 0 1px 3px rgba(0,0,0,.2));
}
[data-theme="dark"] .seg-btn.active { color: #1c1b1f; }
.sm-tip {
  margin: 8px 2px 0;
  font-size: 11px;
  line-height: 1.5;
  color: var(--on-surface-variant);
}
.sm-divider { height: 1px; background: var(--outline-variant); margin: 6px 4px; }
.sm-item {
  display: flex;
  align-items: center;
  gap: 10px;
  width: 100%;
  padding: 10px 10px;
  border: none;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--on-surface);
  font-size: 14px;
  text-align: left;
  cursor: pointer;
  transition: background-color var(--transition);
}
.sm-item:hover { background: var(--surface-container-highest); }
.sm-item .sm-ic { display: inline-flex; align-items: center; justify-content: center; width: 18px; }
.sm-danger { color: var(--error); }
.sm-danger:hover { background: color-mix(in srgb, var(--error) 12%, transparent); }

/* ========================================
   关于 / 学习画像弹窗（炫酷版）
   ======================================== */
.about-card {
  position: relative;
  width: 460px;
  max-width: 100%;
  max-height: calc(100vh - 40px);
  overflow: hidden auto;
  background: var(--surface-container-high);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  animation: settings-pop 200ms cubic-bezier(.2,.8,.2,1);
}
.about-close {
  position: absolute;
  top: 12px;
  right: 12px;
  width: 32px;
  height: 32px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: none;
  border-radius: var(--radius-full);
  background: rgba(255,255,255,.18);
  color: #fff;
  cursor: pointer;
  z-index: 2;
  backdrop-filter: blur(4px);
  transition: background-color var(--transition);
}
.about-close:hover { background: rgba(255,255,255,.32); }

.about-hero {
  position: relative;
  padding: 36px 28px 28px;
  text-align: center;
  color: #fff;
  overflow: hidden;
  background: linear-gradient(140deg, #6750A4 0%, #8E5BC8 52%, #5A7FE0 100%);
}
/* 柔和单色高光，取代原先的彩色极光，与全站简洁观感统一 */
.about-aurora {
  position: absolute;
  inset: 0;
  background:
    radial-gradient(60% 90% at 25% 0%, rgba(255,255,255,.22), transparent 65%),
    radial-gradient(55% 80% at 90% 110%, rgba(255,255,255,.14), transparent 70%);
  pointer-events: none;
}
.about-hero-inner { position: relative; z-index: 1; }
.about-badge {
  width: 56px;
  height: 56px;
  border-radius: var(--radius-full);
  background: rgba(255,255,255,.16);
  border: 1px solid rgba(255,255,255,.28);
  color: #fff;
  -webkit-backdrop-filter: blur(4px);
  backdrop-filter: blur(4px);
}
.about-title { font-size: 22px; font-weight: 700; margin: 14px 0 6px; }
.about-sub { font-size: 13.5px; opacity: .92; line-height: 1.5; max-width: 320px; margin: 0 auto; }

.about-body { padding: 22px 24px 6px; }
.about-stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  margin-bottom: 22px;
}
.about-stat {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  padding: 12px 4px;
  background: var(--surface-container-lowest);
  border-radius: var(--radius-md, 12px);
  border: 1px solid var(--outline-variant);
}
.about-stat .as-ic { display: inline-flex; align-items: center; justify-content: center; color: var(--primary); margin-bottom: 2px; }
.about-stat .as-n {
  font-size: 22px;
  font-weight: 700;
  line-height: 1.1;
  color: var(--primary);
  font-variant-numeric: tabular-nums;
}
.about-stat .as-label { font-size: 11px; color: var(--on-surface-variant); }

.about-block { margin-bottom: 18px; }
.about-block-label {
  display: block;
  font-size: 12px;
  font-weight: 600;
  color: var(--on-surface-variant);
  margin-bottom: 10px;
}
.about-chips { display: flex; flex-wrap: wrap; gap: 8px; }
.about-chip {
  padding: 6px 13px;
  font-size: 12.5px;
  font-weight: 500;
  border-radius: var(--radius-full);
  color: var(--on-surface);
  background: color-mix(in srgb, var(--primary) 14%, var(--surface-container-lowest));
  border: 1px solid color-mix(in srgb, var(--primary) 26%, transparent);
}
.about-note {
  font-size: 13.5px;
  line-height: 1.7;
  color: var(--on-surface);
  background: var(--surface-container-lowest);
  border-left: 3px solid var(--primary);
  border-radius: var(--radius-sm);
  padding: 13px 15px;
  margin-bottom: 6px;
}
.about-foot {
  display: flex;
  flex-direction: column;
  gap: 3px;
  padding: 16px 24px 22px;
  text-align: center;
}
.about-foot-brand { font-size: 13px; font-weight: 600; color: var(--on-surface); }
.about-foot-dim { font-size: 11px; color: var(--on-surface-variant); }

@media (max-width: 480px) {
  .about-stats { grid-template-columns: repeat(2, 1fr); }
}

/* ========================================
   内容审核（管理员）
   ======================================== */
.sm-badge {
  margin-left: auto;
  min-width: 18px;
  height: 18px;
  padding: 0 5px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 11px;
  font-weight: 700;
  line-height: 1;
  color: #fff;
  background: var(--error);
  border-radius: var(--radius-full);
}
.review-modal-box {
  width: 600px;
  max-height: calc(100vh - 48px);
  display: flex;
  flex-direction: column;
}
.rv-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 6px;
}
.rv-head h3 { display: flex; align-items: center; gap: 8px; margin-bottom: 0; }
.rv-tip {
  font-size: 12.5px;
  color: var(--on-surface-variant);
  margin-bottom: 14px;
  line-height: 1.6;
}
.rv-body {
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 10px;
  min-height: 60px;
}
.rv-loading, .rv-empty {
  text-align: center;
  color: var(--on-surface-variant);
  font-size: 13.5px;
  padding: 28px 0;
}
.rv-card {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 12px 14px;
  background: var(--surface-container-lowest);
  border: 1px solid var(--outline-variant);
  border-radius: var(--radius-md);
}
.rv-icon { font-size: 26px; line-height: 1; flex-shrink: 0; }
.rv-info { flex: 1; min-width: 0; }
.rv-info h4 { font-size: 14.5px; font-weight: 600; margin: 0 0 3px; word-break: break-word; }
.rv-meta { font-size: 12px; color: var(--on-surface-variant); margin: 0 0 4px; }
.rv-desc { font-size: 12.5px; color: var(--on-surface); margin: 0; line-height: 1.5; word-break: break-word; }
.rv-actions {
  display: flex;
  flex-direction: column;
  gap: 6px;
  flex-shrink: 0;
}
.rv-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 60px;
  padding: 6px 12px;
  font-size: 12.5px;
  font-weight: 600;
  border: 1px solid var(--outline-variant);
  border-radius: var(--radius-full);
  background: var(--surface-container-high);
  color: var(--on-surface);
  cursor: pointer;
  text-decoration: none;
  text-align: center;
}
.rv-btn:hover { background: var(--surface-container-highest); }
.rv-approve {
  background: color-mix(in srgb, var(--primary) 16%, var(--surface-container-lowest));
  border-color: color-mix(in srgb, var(--primary) 30%, transparent);
  color: var(--primary);
}
.rv-approve:hover { background: var(--primary); color: #fff; }
.rv-reject:hover { background: var(--error); color: #fff; border-color: var(--error); }

@media (max-width: 560px) {
  .rv-card { flex-wrap: wrap; }
  .rv-actions { flex-direction: row; width: 100%; }
  .rv-btn { flex: 1; }
}

/* ========================================
   云盘
   ======================================== */
.drive-back { display: inline-flex; align-items: center; gap: 8px; }
.drive-back .ic { color: var(--on-surface-variant); }
.drive-title {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-size: 15px;
  font-weight: 600;
  color: var(--on-surface);
}
.drive-role-badge {
  font-size: 11.5px;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: var(--radius-full);
  color: var(--on-surface-variant);
  background: var(--surface-container-high);
  border: 1px solid var(--outline-variant);
}
.drive-role-badge.admin {
  color: var(--primary);
  background: color-mix(in srgb, var(--primary) 14%, var(--surface-container-lowest));
  border-color: color-mix(in srgb, var(--primary) 28%, transparent);
}
.drive-main { max-width: 960px; margin: 0 auto; padding: 18px 24px 60px; }

.drive-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 14px;
}
.drive-crumbs { display: flex; align-items: center; flex-wrap: wrap; gap: 2px; min-width: 0; }
.crumb {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  border: none;
  background: transparent;
  color: var(--primary);
  font-size: 14px;
  font-weight: 500;
  padding: 4px 6px;
  border-radius: var(--radius-sm);
  cursor: pointer;
}
.crumb:hover { background: var(--surface-container-high); }
.crumb.current { color: var(--on-surface); font-weight: 600; cursor: default; }
.crumb-sep { color: var(--on-surface-variant); font-size: 13px; }
.drive-actions { display: flex; gap: 8px; flex-shrink: 0; }

.drive-dropzone { position: relative; border-radius: var(--radius-lg); min-height: 200px; }
.drive-dropzone.dragover {
  outline: 2px dashed var(--primary);
  outline-offset: 4px;
  background: color-mix(in srgb, var(--primary) 7%, transparent);
}
.drive-drop-hint {
  display: none;
  position: absolute;
  inset: 0;
  align-items: center;
  justify-content: center;
  font-size: 15px;
  font-weight: 600;
  color: var(--primary);
  pointer-events: none;
}
.drive-dropzone.dragover .drive-drop-hint { display: flex; }

.drive-list { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 2px; }
.drive-loading, .drive-empty {
  color: var(--on-surface-variant);
  font-size: 13.5px;
  text-align: center;
  padding: 40px 0;
  list-style: none;
}
.drive-item {
  display: flex;
  align-items: center;
  gap: 13px;
  padding: 11px 12px;
  border-radius: var(--radius-md);
  transition: background 120ms;
}
.drive-item:hover { background: var(--surface-container-low); }
.di-icon {
  flex-shrink: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 30px;
}
.drive-item.is-dir .di-icon { color: var(--primary); }
.drive-item.is-file .di-icon { color: var(--on-surface-variant); }
.di-main { flex: 1; min-width: 0; display: flex; flex-direction: column; gap: 1px; }
.di-name {
  font-size: 14.5px;
  font-weight: 500;
  color: var(--on-surface);
  text-align: left;
  border: none;
  background: transparent;
  padding: 0;
  cursor: pointer;
  text-decoration: none;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.di-name:hover { color: var(--primary); text-decoration: underline; }
.di-meta { font-size: 12px; color: var(--on-surface-variant); }
.di-actions { display: flex; gap: 4px; flex-shrink: 0; opacity: 0; transition: opacity 120ms; }
.drive-item:hover .di-actions, .drive-item:focus-within .di-actions { opacity: 1; }
.di-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border: none;
  background: transparent;
  color: var(--on-surface-variant);
  border-radius: var(--radius-full);
  cursor: pointer;
  text-decoration: none;
}
.di-btn:hover { background: var(--surface-container-highest); color: var(--on-surface); }
.di-del:hover { background: var(--error); color: #fff; }
@media (hover: none) { .di-actions { opacity: 1; } }

.drive-uploads {
  position: fixed;
  right: 20px;
  bottom: 20px;
  width: 320px;
  max-width: calc(100vw - 40px);
  background: var(--surface-container-high);
  border: 1px solid var(--outline-variant);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  padding: 10px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  z-index: 80;
}
.up-row { display: grid; grid-template-columns: 1fr auto; grid-template-rows: auto auto; gap: 2px 8px; align-items: center; }
.up-name { font-size: 12.5px; color: var(--on-surface); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.up-pct { font-size: 12px; color: var(--on-surface-variant); grid-row: 1; grid-column: 2; }
.up-bar { grid-column: 1 / -1; height: 4px; border-radius: var(--radius-full); background: var(--surface-container-highest); overflow: hidden; }
.up-bar i { display: block; height: 100%; background: var(--primary); transition: width 120ms; }
.up-row.done .up-pct { color: var(--primary); }
.up-row.done.pending .up-pct { color: #c77800; font-size: 11px; font-weight: 600; }
.up-row.done.pending .up-bar i { background: #e0902a; }
.up-row.err .up-pct, .up-row.err .up-name { color: var(--error); }

@media (max-width: 520px) {
  .drive-main { padding: 14px 14px 60px; }
  .drive-bar { flex-direction: column; align-items: stretch; }
  .drive-tools { flex-wrap: wrap; }
  .drive-actions { justify-content: flex-end; }
  .drive-actions .pill-label { display: none; }
}

/* ---- 云盘工具栏：搜索 / 排序 / 容量 ---- */
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0,0,0,0); border: 0; }
.drive-tools { display: flex; align-items: center; gap: 8px; flex-shrink: 0; }
.drive-search {
  display: flex; align-items: center; gap: 6px;
  padding: 5px 10px;
  background: var(--surface-container-high);
  border: 1px solid var(--outline-variant);
  border-radius: var(--radius-full);
  color: var(--on-surface-variant);
}
.drive-search input { border: none; background: transparent; color: var(--on-surface); font-size: 13px; width: 130px; outline: none; }
.drive-sort { display: flex; align-items: center; gap: 4px; }
.drive-sort select {
  padding: 6px 8px; font-size: 13px;
  background: var(--surface-container-high);
  border: 1px solid var(--outline-variant);
  border-radius: var(--radius-sm);
  color: var(--on-surface); cursor: pointer;
}
#drive-sort-dir .nbi { transition: transform 150ms; }
#drive-sort-dir.desc .nbi { transform: rotate(180deg); }
.drive-foot { margin-top: 18px; font-size: 12px; color: var(--on-surface-variant); }
.quota-head { display: flex; justify-content: space-between; gap: 10px; margin-bottom: 6px; flex-wrap: wrap; }
.quota-bar { height: 8px; border-radius: var(--radius-full); background: var(--surface-container-highest); overflow: hidden; }
.quota-bar i { display: block; height: 100%; background: var(--primary); border-radius: var(--radius-full); transition: width 200ms; }

/* 对外可见开关 + 仅管理员可见的暗显 */
.drive-item .di-actions { opacity: 1; }
.di-vis {
  font-size: 11px; font-weight: 600; padding: 3px 9px; flex-shrink: 0;
  border-radius: var(--radius-full); border: 1px solid var(--outline-variant);
  background: var(--surface-container-high); color: var(--on-surface-variant); cursor: pointer;
}
.di-vis.on {
  background: color-mix(in srgb, var(--primary) 16%, var(--surface-container-lowest));
  border-color: color-mix(in srgb, var(--primary) 30%, transparent); color: var(--primary);
}

/* 拖拽移动：高亮目标文件夹 / 面包屑 */
.drive-item.drag-target { outline: 2px solid var(--primary); outline-offset: -2px; background: color-mix(in srgb, var(--primary) 10%, transparent); border-radius: var(--radius-md); }
.crumb.drag-target { background: color-mix(in srgb, var(--primary) 22%, transparent); }
.drive-item[draggable="true"] { cursor: grab; }

/* ---- 分享：创建弹窗 ---- */
.share-form { display: flex; flex-direction: column; gap: 2px; }
.share-form select, .share-form input {
  width: 100%; padding: 9px 11px; font-size: 14px;
  border: 1px solid var(--outline-variant); border-radius: var(--radius-sm);
  background: var(--surface-container-lowest); color: var(--on-surface);
}
.share-result { margin: 14px 0 4px; font-size: 13px; color: var(--on-surface-variant); }
.share-link-row { display: flex; gap: 8px; margin-top: 8px; }
.share-link-row input {
  flex: 1; padding: 9px 11px; font-size: 13px;
  border: 1px solid var(--outline-variant); border-radius: var(--radius-sm);
  background: var(--surface-container-lowest); color: var(--on-surface);
}

/* ---- 分享：管理列表标签 ---- */
.sh-tag {
  display: inline-block; font-size: 11.5px; padding: 2px 8px; margin-right: 4px;
  border-radius: var(--radius-full);
  background: var(--surface-container-high); color: var(--on-surface-variant);
}
.sh-tag.err { background: color-mix(in srgb, var(--error) 16%, transparent); color: var(--error); }

/* ---- 文件预览弹窗 ---- */
.preview-box {
  width: min(960px, 96vw); height: min(86vh, 900px);
  background: var(--surface-container-high);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  display: flex; flex-direction: column; overflow: hidden;
}
.preview-head {
  display: flex; align-items: center; justify-content: space-between;
  gap: 12px; padding: 12px 16px; border-bottom: 1px solid var(--outline-variant);
}
.preview-name { font-size: 14.5px; font-weight: 600; color: var(--on-surface); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.preview-actions { display: flex; gap: 4px; flex-shrink: 0; }
.preview-body { flex: 1; min-height: 0; display: flex; align-items: center; justify-content: center; background: var(--surface-container-lowest); overflow: auto; }
.preview-body img { max-width: 100%; max-height: 100%; object-fit: contain; }
.preview-body video { max-width: 100%; max-height: 100%; }
.preview-body iframe { width: 100%; height: 100%; border: 0; background: #fff; }
#review-btn .sm-badge { margin-left: 4px; }
.preview-audio { padding: 0 16px; }
.preview-audio audio { width: min(520px, 86vw); }
.preview-none { color: var(--on-surface-variant); font-size: 14px; line-height: 1.7; text-align: center; padding: 40px; }
.preview-none a.btn-confirm { display: inline-block; text-decoration: none; margin-top: 6px; }

/* ---- 公开分享访问页 ---- */
.ds-gate { display: flex; justify-content: center; padding: 60px 16px; }
.ds-gate-card {
  width: 340px; max-width: 100%; text-align: center;
  background: var(--surface-container-high);
  border: 1px solid var(--outline-variant); border-radius: var(--radius-lg);
  padding: 28px 24px; box-shadow: var(--shadow-md);
}
.ds-gate-ic { color: var(--primary); display: inline-flex; margin-bottom: 10px; }
.ds-gate-card h3 { font-size: 16px; margin-bottom: 16px; }
.ds-gate-card input {
  width: 100%; padding: 10px 12px; font-size: 14px; margin-bottom: 10px;
  border: 1px solid var(--outline-variant); border-radius: var(--radius-sm);
  background: var(--surface-container-lowest); color: var(--on-surface);
}
.ds-gate-card .btn-confirm { width: 100%; }
.ds-gate-err { color: var(--error); font-size: 12.5px; margin-bottom: 10px; }
.ds-file { margin-top: 12px; }
.ds-file-head {
  display: flex; align-items: center; gap: 12px;
  padding: 14px; background: var(--surface-container-low);
  border-radius: var(--radius-md);
}
.ds-file-head .di-icon { color: var(--on-surface-variant); }
.ds-file-name { font-size: 15px; font-weight: 600; color: var(--on-surface); }
.ds-prev-wrap { margin-top: 14px; border: 1px solid var(--outline-variant); border-radius: var(--radius-md); overflow: hidden; background: var(--surface-container-lowest); }
.ds-prev { display: block; width: 100%; }
img.ds-prev { max-height: 70vh; object-fit: contain; }
iframe.ds-prev { height: 75vh; border: 0; background: #fff; }
video.ds-prev { max-height: 70vh; background: #000; }

/* ========================================
   群聊页（body.room）
   ======================================== */
body.room {
  height: 100vh;
  display: flex;
  flex-direction: column;
  background: var(--surface-container-low);
  overflow: hidden;
}
.room-bar {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 20px;
  border-bottom: 1px solid var(--outline-variant);
  background: var(--surface-container);
  flex: none;
}
.room-back {
  width: 38px; height: 38px; flex: none;
  display: inline-flex; align-items: center; justify-content: center;
  border-radius: var(--radius-full); font-size: 19px; color: var(--on-surface);
  transition: background-color var(--transition);
}
.room-back:hover { background: var(--surface-container-high); }
.room-head { flex: 1; min-width: 0; display: flex; flex-direction: column; gap: 1px; }
.room-title { font-size: 16px; font-weight: 600; }
.room-sub { font-size: 12px; color: var(--on-surface-variant); }

.room-main {
  flex: 1;
  overflow-y: auto;
  padding: 18px 16px 8px;
  display: flex;
  flex-direction: column;
}
.room-main > #room-msgs { margin-top: auto; display: flex; flex-direction: column; gap: 12px; }
.room-empty { margin: auto; color: var(--on-surface-variant); font-size: 14px; }

.room-msg {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  max-width: min(760px, 92%);
}
.room-msg.mine { align-self: flex-end; flex-direction: row-reverse; }
.room-avatar {
  flex: none;
  width: 34px; height: 34px;
  border-radius: 50%;
  display: inline-flex; align-items: center; justify-content: center;
  color: #fff; font-size: 15px; font-weight: 600;
  margin-top: 16px;
}
.room-body { min-width: 0; display: flex; flex-direction: column; gap: 3px; }
.room-meta { display: flex; align-items: baseline; gap: 8px; padding: 0 2px; }
.room-msg.mine .room-meta { flex-direction: row-reverse; }
.room-name { font-size: 12px; font-weight: 600; }
.room-time { font-size: 11px; color: var(--on-surface-variant); font-variant-numeric: tabular-nums; }
.room-bubble {
  padding: 9px 13px;
  border-radius: 14px;
  font-size: 14px;
  line-height: 1.6;
  white-space: pre-wrap;
  word-break: break-word;
  background: var(--surface-container-highest);
  color: var(--on-surface);
  border-top-left-radius: 4px;
}
.room-msg.mine .room-bubble {
  background: var(--primary);
  color: var(--on-primary);
  border-top-left-radius: 14px;
  border-top-right-radius: 4px;
}

.room-form {
  flex: none;
  display: flex;
  align-items: flex-end;
  gap: 10px;
  padding: 12px 16px;
  border-top: 1px solid var(--outline-variant);
  background: var(--surface-container);
}
#room-input {
  flex: 1;
  resize: none;
  border: 1px solid var(--outline-variant);
  border-radius: 14px;
  padding: 10px 14px;
  font: inherit;
  font-size: 14px;
  line-height: 1.5;
  background: var(--surface-container-lowest);
  color: var(--on-surface);
  max-height: 140px;
  outline: none;
}
#room-input:focus { border-color: var(--primary); }
#room-send {
  flex: none;
  width: 42px; height: 42px;
  border: none;
  border-radius: 50%;
  background: var(--primary);
  color: var(--on-primary);
  font-size: 18px;
  cursor: pointer;
  transition: filter var(--transition);
}
#room-send:hover { filter: brightness(1.06); }

@media (max-width: 640px) {
  .room-bar { padding: 10px 14px; }
}
/* ========================================
   主页动态背景（设置 → 动态背景）
   ======================================== */
:root[data-bg]:not([data-bg="none"]) body.home { background-color: transparent; }
/* 顶栏必须高于课程区：经典模式的设置/创建菜单仍挂在顶栏内。 */
body.home > .topbar { position: relative; z-index: 70; }
body.home > main { position: relative; z-index: 1; }
.nb-background-canvas {
  position: fixed; inset: 0; z-index: 0;
  width: 100vw; height: 100vh;
  pointer-events: none;
  opacity: .54;
  filter: saturate(1.05);
  transition: opacity 240ms ease;
}
[data-theme="dark"] .nb-background-canvas { opacity: .82; filter: saturate(1.14) brightness(.92); }
:root[data-ui="premium"][data-bg]:not([data-bg="none"]) body.home::before { opacity: .22; }

/* WebGL 不可用时仍保留对应的静态氛围，不退回一片空白。 */
:root.nb-bg-fallback[data-bg="aurora"] body.home {
  background-image: radial-gradient(70vw 38vh at 22% 18%, #7cff6766, transparent 70%), radial-gradient(62vw 42vh at 72% 28%, #5227ff70, transparent 72%);
}
:root.nb-bg-fallback[data-bg="balatro"] body.home {
  background-image: conic-gradient(from 210deg at 54% 34%, #11131c, #7d29ff55, #0b91ff66, #11131c);
}
.settings-menu {
  width: 286px;
  max-height: calc(100vh - 92px);
  overflow: auto;
  scrollbar-width: thin;
}
.bg-picker {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 7px;
}
.bg-choice {
  position: relative;
  display: grid;
  gap: 5px;
  min-width: 0;
  padding: 5px 5px 7px;
  border: 1px solid var(--outline-variant);
  border-radius: 11px;
  background: color-mix(in srgb, var(--surface-container-lowest) 76%, transparent);
  color: var(--on-surface-variant);
  font: 600 10px/1.1 inherit;
  cursor: pointer;
  transition: border-color var(--transition), color var(--transition), transform var(--transition), background-color var(--transition);
}
.bg-choice:hover {
  color: var(--on-surface);
  border-color: color-mix(in srgb, var(--primary) 48%, var(--outline-variant));
  transform: translateY(-1px);
}
.bg-choice.active {
  color: var(--primary);
  border-color: var(--primary);
  background: color-mix(in srgb, var(--primary) 10%, var(--surface-container-lowest));
  box-shadow: 0 0 0 1px color-mix(in srgb, var(--primary) 24%, transparent);
}
.bg-choice.active::after {
  content: '✓';
  position: absolute;
  top: 7px; right: 7px;
  display: grid; place-items: center;
  width: 14px; height: 14px;
  border-radius: 50%;
  background: color-mix(in srgb, var(--surface) 74%, transparent);
  color: var(--primary);
  font-size: 9px;
}
.bg-thumb {
  display: block;
  width: 100%; height: 31px;
  overflow: hidden;
  border-radius: 7px;
  background-color: #0b0c17;
  box-shadow: inset 0 0 0 1px rgba(255,255,255,.10);
}
.bg-thumb-none {
  background: linear-gradient(135deg, var(--surface-container-lowest) 0 50%, var(--surface-container-high) 50%);
}
.bg-thumb-aurora {
  background: radial-gradient(70% 90% at 16% 34%, #7cff67cc, transparent 72%), radial-gradient(90% 90% at 76% 50%, #5227ff, #0b0c17 72%);
}
.bg-thumb-balatro {
  background: repeating-radial-gradient(ellipse at 58% 50%, #7028ff 0 9%, #078eff 12%, #121322 20%);
}
@media (max-width: 520px) {
  .settings-menu { width: min(286px, calc(100vw - 24px)); max-height: calc(100dvh - 86px); }
  .nb-background-canvas { opacity: .45; }
  [data-theme="dark"] .nb-background-canvas { opacity: .72; }
}
