/* ============================================================
 *  /books/ 文献阅读工作台 —— 样式
 *  配色沿用站点「蓝灰」体系；明暗两套令牌由 html[data-theme] 驱动，
 *  与主站主题共用同一个 localStorage 键（theme），偏好双向互通。
 * ============================================================ */

/* Font Awesome 已由 /css/vendor/fontawesome.min.css 本地提供；
   这里只兜底：若未加载也不至于把图标渲染成斜体文字 */
.bk-page-body i[class*="fa-"] { font-style: normal; }

/* ------------------------------------------------------------
 * 令牌：浅色（默认）
 * 命名保持 --bk-* 不变，这样 reader.css 全文无需改写，
 * 只把语义映射到 --bg-* / --fg-* 即可整体换肤。
 * ---------------------------------------------------------- */
.bk-page-body {
  --bk-bg-0: #e9eef5;                          /* 最底层（工作区外框） */
  --bk-bg-1: #f3f6fa;                          /* 顶栏 / 工具条 */
  --bk-bg-2: #fbfcfe;                          /* 面板 / 卡片 */
  --bk-bg-3: #ffffff;                          /* 悬浮层 / 输入框 */
  --bk-line: rgba(126, 150, 184, .30);
  --bk-line-strong: rgba(126, 150, 184, .46);
  --bk-fg: #1d2836;
  --bk-fg-dim: #4c5c70;
  --bk-fg-mute: #7b8a9c;
  --bk-accent: #5c7ba6;
  --bk-accent-2: #3f5d86;
  --bk-amber: #b8860b;                         /* 浅底上需压暗才够对比 */
  --bk-radius: 14px;
  --bk-shadow: 0 18px 48px rgba(40, 55, 80, .16);
  --bk-topbar-h: 58px;
  --bk-rail-h: 44px;
  --bk-right-w: 420px;

  /* 叠加层：深色下是「加白提亮」，浅色下必须反转为「加黑压暗」。
     全部收敛到这两个变量，reader.css 里不再直写 rgba(255,255,255,x) */
  --bk-tint: rgba(18, 32, 54, .045);            /* 中性底纹：输入框/卡片 */
  --bk-tint-hover: rgba(18, 32, 54, .085);      /* 悬停底纹 */
  --bk-tint-strong: rgba(18, 32, 54, .12);      /* 选中/强调底纹 */

  /* 强调文字色：本质是「加深」——浅色下加深 = 变暗，深色下加深 = 变亮。
     专门用于「悬停/选中时把文字提亮到最醒目」这个语义。
     ⚠️ 它与 --bk-accent-2 的差别：accent-2 是品牌蓝、始终有彩色倾向；
     on-accent 在两套主题下都趋向「纯前景极值」，用于 hover 提亮更自然。 */
  --bk-stronger: #0f1a26;

  margin: 0;
  padding: 0;
  background: var(--bk-bg-0);
  color: var(--bk-fg);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  font-size: 15px;
  line-height: 1.6;
  overflow: hidden;
  /* 覆盖主题可能残留的 body 样式 */
  height: 100vh;
  min-height: 100vh;
}

/* ------------------------------------------------------------
 * 令牌：深色（与改造前的观感逐值对齐，老用户无感）
 * ---------------------------------------------------------- */
html[data-theme='dark'] .bk-page-body {
  --bk-bg-0: #131a26;
  --bk-bg-1: #1a2230;
  --bk-bg-2: #212c3e;
  --bk-bg-3: #2a374d;
  --bk-line: rgba(157, 180, 211, .18);
  --bk-line-strong: rgba(157, 180, 211, .34);
  --bk-fg: #e9edf3;
  --bk-fg-dim: #b9c5d6;
  --bk-fg-mute: #8497b0;
  --bk-accent: #7e96b8;
  --bk-accent-2: #9db4d3;
  --bk-amber: #ffd666;
  --bk-shadow: 0 18px 48px rgba(6, 10, 18, .42);

  --bk-tint: rgba(255, 255, 255, .05);
  --bk-tint-hover: rgba(255, 255, 255, .10);
  --bk-tint-strong: rgba(255, 255, 255, .12);
  --bk-stronger: #ffffff;
}


.bk-page-body *,
.bk-page-body *::before,
.bk-page-body *::after { box-sizing: border-box; }

.bk-page-body a { color: var(--bk-accent-2); text-decoration: none; }
.bk-page-body a:hover { color: var(--bk-stronger); }

.bk-page-body ::-webkit-scrollbar { width: 10px; height: 10px; }
.bk-page-body ::-webkit-scrollbar-track { background: transparent; }
.bk-page-body ::-webkit-scrollbar-thumb {
  background: var(--bk-tint-strong);
  border: 2px solid transparent;
  border-radius: 8px;
  background-clip: content-box;
}
.bk-page-body ::-webkit-scrollbar-thumb:hover { background-color: var(--bk-line-strong); background-clip: content-box; }

/* ---------------- 通用控件 ---------------- */

.bk-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  height: 34px;
  padding: 0 12px;
  border: 1px solid var(--bk-line-strong);
  border-radius: 9px;
  background: var(--bk-tint);
  color: var(--bk-fg);
  font: inherit;
  font-size: 13.5px;
  line-height: 1;
  cursor: pointer;
  white-space: nowrap;
  transition: background .16s ease, border-color .16s ease, transform .16s ease;
}
.bk-btn:hover { background: var(--bk-tint-hover); border-color: var(--bk-line-strong); }
.bk-btn:active { transform: translateY(1px); }
.bk-btn-primary {
  border-color: transparent;
  /* 渐变底本身就是深蓝灰，在明暗两套主题下都足够深，白字对比度始终达标，
     因此这里刻意直写 #fff 而不是走 --bk-stronger（后者浅色下是深色） */
  background: linear-gradient(120deg, #7e96b8, #9db4d3);
  color: #fff;
  font-weight: 700;
}
.bk-btn-primary:hover { background: linear-gradient(120deg, var(--bk-accent), var(--bk-accent-2)); }
.bk-btn-ghost { background: transparent; border-color: var(--bk-line); color: var(--bk-fg-dim); }
.bk-btn-ghost:hover { color: var(--bk-stronger); }
.bk-btn-sm { height: 30px; padding: 0 10px; font-size: 12.5px; border-radius: 8px; }

.bk-ic {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border: 1px solid transparent;
  border-radius: 8px;
  background: transparent;
  color: var(--bk-fg-dim);
  font: inherit;
  font-size: 14px;
  cursor: pointer;
  transition: background .16s ease, color .16s ease;
}
.bk-ic:hover { background: var(--bk-tint-hover); color: var(--bk-stronger); }

.bk-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 17px;
  height: 17px;
  margin-left: 4px;
  padding: 0 5px;
  border-radius: 9px;
  background: var(--bk-line);
  color: #dce6f5;
  font-size: 10.5px;
  font-style: normal;
  font-weight: 700;
  line-height: 1;
}
.bk-badge:empty { display: none; }

.bk-sep { width: 1px; height: 18px; margin: 0 4px; background: var(--bk-line); }

.bk-spin {
  display: inline-block;
  width: 12px;
  height: 12px;
  border: 2px solid var(--bk-line);
  border-top-color: var(--bk-accent-2);
  border-radius: 50%;
  animation: bkSpin .7s linear infinite;
  vertical-align: -1px;
}
@keyframes bkSpin { to { transform: rotate(360deg); } }

/* ---------------- 顶栏 ---------------- */

.bk-topbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 40;
  display: flex;
  align-items: center;
  gap: 14px;
  height: var(--bk-topbar-h);
  padding: 0 16px;
  border-bottom: 1px solid var(--bk-line);
  background: rgba(19, 26, 38, .9);
  -webkit-backdrop-filter: blur(16px) saturate(120%);
  backdrop-filter: blur(16px) saturate(120%);
}

.bk-brand {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--bk-stronger);
  font-size: 15px;
  font-weight: 700;
  letter-spacing: .01em;
  white-space: nowrap;
}
.bk-brand i { color: var(--bk-accent-2); }

.bk-open {
  display: flex;
  flex: 1 1 auto;
  align-items: center;
  gap: 8px;
  min-width: 0;
}

.bk-file-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  height: 34px;
  padding: 0 12px;
  border: 1px dashed var(--bk-line-strong);
  border-radius: 9px;
  color: var(--bk-fg-dim);
  font-size: 13.5px;
  cursor: pointer;
  white-space: nowrap;
  transition: border-color .16s ease, color .16s ease, background .16s ease;
}
.bk-file-btn:hover { border-color: var(--bk-accent-2); color: var(--bk-stronger); background: var(--bk-tint); }

.bk-input-wrap {
  display: flex;
  flex: 1 1 auto;
  align-items: center;
  gap: 6px;
  min-width: 0;
  max-width: 620px;
  padding: 3px 3px 3px 12px;
  border: 1px solid var(--bk-line-strong);
  border-radius: 11px;
  background: var(--bk-tint);
  transition: border-color .18s ease, box-shadow .18s ease;
}
.bk-input-wrap:focus-within {
  border-color: var(--bk-line-strong);
  box-shadow: 0 0 0 3px var(--bk-tint-strong);
}
.bk-input-wrap input {
  flex: 1 1 auto;
  min-width: 0;
  height: 28px;
  border: 0;
  outline: none;
  background: transparent;
  color: var(--bk-stronger);
  font: inherit;
  font-size: 13.5px;
}
.bk-input-wrap input::placeholder { color: var(--bk-fg-mute); }

.bk-topbar-right {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-left: auto;
}

/* ---------------- 主体两栏 ---------------- */

.bk-workspace {
  position: fixed;
  top: var(--bk-topbar-h);
  right: 0; bottom: 0; left: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr) var(--bk-right-w);
  transition: grid-template-columns .24s ease;
}
.bk-workspace.is-collapsed { grid-template-columns: minmax(0, 1fr) 0px; }
.bk-workspace.is-collapsed .bk-right { opacity: 0; pointer-events: none; border-left-color: transparent; }

.bk-workspace.is-dragging .bk-scroller { outline: 2px dashed var(--bk-accent-2); outline-offset: -10px; }

/* ---------------- 左侧 ---------------- */

.bk-left {
  position: relative;
  display: flex;
  flex-direction: column;
  min-width: 0;
  background: var(--bk-bg-1);
  border-right: 1px solid var(--bk-line);
}

.bk-toolbar {
  display: flex;
  align-items: center;
  gap: 2px;
  height: var(--bk-rail-h);
  padding: 0 10px;
  border-bottom: 1px solid var(--bk-line);
  background: rgba(26, 34, 48, .82);
  flex: 0 0 auto;
  overflow-x: auto;
  scrollbar-width: none;
}
.bk-toolbar::-webkit-scrollbar { display: none; }

.bk-page-label {
  min-width: 56px;
  color: var(--bk-fg-dim);
  font-size: 12.5px;
  font-variant-numeric: tabular-nums;
  text-align: center;
  white-space: nowrap;
}

.bk-scroller {
  position: relative;
  flex: 1 1 auto;
  overflow: auto;
  padding: 22px 28px 90px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 22px;
  scroll-behavior: smooth;
}

/* 页面容器：canvas + 文本层 + 高亮层 三层叠加 */
.bk-page {
  position: relative;
  flex: 0 0 auto;
  background: #fff;
  border-radius: 6px;
  box-shadow: 0 10px 34px rgba(4, 8, 14, .5);
  overflow: hidden;
}
.bk-page-error {
  display: grid;
  place-items: center;
  min-height: 320px;
  padding: 24px;
  color: #8b3a3a;
  font-size: 14px;
  text-align: center;
}

.bk-canvas-wrap {
  position: relative;
  width: 100%;
  height: 100%;
}
.bk-canvas { display: block; }

/* 高亮层：在文本层之上，但允许鼠标穿透（选字交给 textLayer） */
.bk-hl-layer {
  position: absolute;
  inset: 0;
  pointer-events: none;
  z-index: 3;
}
.bk-hl {
  position: absolute;
  border-radius: 2px;
  opacity: .42;
  mix-blend-mode: multiply;
}
.bk-hl[data-type="underline"],
.bk-hl[data-type="strike"] {
  background: transparent !important;
  opacity: 1;
  mix-blend-mode: normal;
  height: 0 !important;
}
.bk-hl.has-note::after {
  content: "";
  position: absolute;
  right: -2px;
  bottom: -2px;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: #1f8f6a;
  box-shadow: 0 0 0 1.5px #fff;
}
.bk-hl.is-flash { animation: bkFlash 1s ease 2; }
@keyframes bkFlash { 50% { opacity: .95; } }

/* 拖入提示层 */
.bk-dropzone {
  display: grid;
  place-items: center;
  width: 100%;
  min-height: 100%;
  padding: 30px;
  cursor: pointer;
}
.bk-page .bk-canvas-wrap ~ .bk-dropzone { display: none; }
.bk-dropzone { margin: auto; }

/* 打开文献后隐藏空态；没打开文献时也不堆一屏提示 */
.bk-workspace.is-ready .bk-dropzone,
.bk-workspace.is-ready .bk-recent { display: none; }
.bk-drop-inner {
  width: min(100%, 480px);
  padding: 34px 30px;
  border: 1px solid var(--bk-line-strong);
  border-radius: 20px;
  background: rgba(20, 27, 40, .6);
  text-align: center;
}
.bk-drop-inner i.fa-file-pdf {
  font-size: 40px;
  color: var(--bk-accent-2);
  opacity: .9;
}
.bk-drop-inner h3 { margin: 12px 0 8px; color: var(--bk-stronger); font-size: 1.08rem; }
.bk-drop-inner p { margin: 0; color: var(--bk-fg-dim); font-size: 13.5px; line-height: 1.8; }
.bk-drop-tips {
  margin: 18px 0 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 6px;
  color: var(--bk-fg-mute);
  font-size: 13px;
}
.bk-drop-tips li::before { content: "· "; color: var(--bk-accent-2); }

/* ---------------- 右侧栏 ---------------- */

.bk-right {
  display: flex;
  flex-direction: column;
  min-width: 0;
  background: var(--bk-bg-2);
  border-left: 1px solid var(--bk-line);
  transition: opacity .2s ease;
}

.bk-dochead {
  flex: 0 0 auto;
  padding: 16px 18px 14px;
  border-bottom: 1px solid var(--bk-line);
  background: rgba(19, 26, 38, .34);
}
.bk-doc-title {
  margin: 0;
  color: var(--bk-stronger);
  font-size: 15.5px;
  font-weight: 700;
  line-height: 1.45;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.bk-doc-meta {
  margin: 6px 0 0;
  color: var(--bk-fg-mute);
  font-size: 12.5px;
  line-height: 1.6;
}
.bk-doc-doi { margin: 4px 0 0; font-size: 12.5px; color: var(--bk-fg-mute); }

.bk-tabs {
  display: flex;
  flex: 0 0 auto;
  gap: 2px;
  padding: 8px 10px 0;
  border-bottom: 1px solid var(--bk-line);
}
.bk-tab {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 7px 10px 10px;
  border: 0;
  background: transparent;
  color: var(--bk-fg-mute);
  font: inherit;
  font-size: 13px;
  cursor: pointer;
  white-space: nowrap;
  transition: color .16s ease;
}
.bk-tab:hover { color: var(--bk-fg); }
/* 选中态文字用强调色（而非白色）——白色在浅色底上会看不见 */
.bk-tab.is-on { color: var(--bk-accent-2); font-weight: 700; }
.bk-tab.is-on::after {
  content: "";
  position: absolute;
  right: 6px; bottom: -1px; left: 6px;
  height: 2px;
  border-radius: 2px;
  background: linear-gradient(90deg, #7e96b8, #9db4d3);
}

.bk-pane {
  display: none;
  flex: 1 1 auto;
  min-height: 0;
  overflow-y: auto;
  padding: 12px 14px 40px;
}
.bk-pane.is-on { display: block; }

.bk-pane-actions {
  display: flex;
  gap: 8px;
  margin-bottom: 12px;
  flex-wrap: wrap;
}

.bk-empty {
  margin: 10px 2px;
  padding: 16px 14px;
  border: 1px dashed var(--bk-line);
  border-radius: 10px;
  color: var(--bk-fg-mute);
  font-size: 13px;
  line-height: 1.8;
}

/* 随手笔记卡片 */
.bk-note {
  margin-bottom: 10px;
  padding: 10px 12px;
  border: 1px solid var(--bk-line);
  border-radius: 11px;
  background: var(--bk-tint);
  transition: border-color .16s ease;
}
.bk-note:focus-within { border-color: var(--bk-line-strong); }
.bk-note-head { display: flex; align-items: center; gap: 8px; }
.bk-note-title {
  flex: 1 1 auto;
  min-width: 0;
  height: 26px;
  border: 0;
  border-bottom: 1px dashed transparent;
  outline: none;
  background: transparent;
  color: var(--bk-stronger);
  font: inherit;
  font-size: 13.5px;
  font-weight: 700;
}
.bk-note-title:focus { border-bottom-color: var(--bk-line-strong); }
.bk-note-page {
  padding: 1px 7px;
  border-radius: 20px;
  background: var(--bk-tint-strong);
  color: var(--bk-fg-dim);
  font-size: 11px;
  white-space: nowrap;
}
.bk-note-del,
.bk-ann-del {
  width: 24px; height: 24px;
  border: 0;
  border-radius: 6px;
  background: transparent;
  color: var(--bk-fg-mute);
  font-size: 16px;
  line-height: 1;
  cursor: pointer;
}
.bk-note-del:hover,
.bk-ann-del:hover { background: rgba(220, 90, 90, .18); color: #ff9f9f; }
.bk-note-text,
.bk-ann-note {
  width: 100%;
  margin-top: 6px;
  padding: 8px 10px;
  border: 1px solid var(--bk-line);
  border-radius: 9px;
  outline: none;
  background: rgba(12, 18, 28, .5);
  color: var(--bk-fg);
  font: inherit;
  font-size: 13.5px;
  line-height: 1.75;
  resize: vertical;
}
.bk-note-text:focus,
.bk-ann-note:focus { border-color: var(--bk-line-strong); }

/* 标注卡片 */
.bk-ann {
  margin-bottom: 10px;
  padding: 9px 11px;
  border: 1px solid var(--bk-line);
  border-left: 3px solid rgba(255, 214, 102, .7);
  border-radius: 10px;
  background: var(--bk-tint);
  transition: border-color .16s ease, background .16s ease;
}
.bk-ann.is-active { border-color: var(--bk-line-strong); background: var(--bk-tint); }
.bk-ann-head {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 5px;
  font-size: 11.5px;
  color: var(--bk-fg-mute);
}
.bk-ann-page { color: var(--bk-accent-2); font-weight: 700; cursor: pointer; }
.bk-ann-type { padding: 1px 6px; border-radius: 20px; background: var(--bk-tint-hover); }
.bk-ann-index { margin-left: auto; }
.bk-ann-quote {
  margin: 0;
  color: var(--bk-fg);
  font-size: 13.5px;
  line-height: 1.7;
  cursor: pointer;
  display: -webkit-box;
  -webkit-line-clamp: 4;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.bk-ann-quote:hover { color: var(--bk-stronger); }

/* 中英对照 */
.bk-bi-row {
  margin-bottom: 12px;
  padding: 10px 12px;
  border: 1px solid var(--bk-line);
  border-radius: 10px;
  background: var(--bk-tint);
}
.bk-bi-src {
  margin: 0 0 7px;
  color: var(--bk-fg-dim);
  font-size: 13px;
  line-height: 1.7;
  font-family: "Iowan Old Style", "Palatino Linotype", Georgia, serif;
}
.bk-bi-dst {
  margin: 0;
  padding-top: 7px;
  border-top: 1px dashed var(--bk-line);
  color: var(--bk-stronger);
  font-size: 14px;
  line-height: 1.8;
}
.bk-bi-row.is-pending { opacity: .7; }
.bk-bi-row.is-error .bk-bi-dst { color: #ff9f9f; }

/* ---------------- 设置表单 ---------------- */

.bk-form h4 {
  margin: 4px 0 6px;
  color: var(--bk-stronger);
  font-size: 13.5px;
  font-weight: 700;
}
.bk-hint {
  margin: 0 0 14px;
  padding: 9px 11px;
  border-left: 3px solid var(--bk-line-strong);
  border-radius: 0 8px 8px 0;
  background: var(--bk-tint);
  color: var(--bk-fg-mute);
  font-size: 12px;
  line-height: 1.75;
}
.bk-form label {
  display: block;
  margin-bottom: 12px;
  color: var(--bk-fg-dim);
  font-size: 12.5px;
}
.bk-form input,
.bk-form select {
  display: block;
  width: 100%;
  height: 36px;
  margin-top: 5px;
  padding: 0 11px;
  border: 1px solid var(--bk-line-strong);
  border-radius: 9px;
  outline: none;
  background: rgba(12, 18, 28, .5);
  color: var(--bk-stronger);
  font: inherit;
  font-size: 13.5px;
}
.bk-form input:focus,
.bk-form select:focus {
  border-color: var(--bk-line-strong);
  box-shadow: 0 0 0 3px var(--bk-tint-strong);
}
.bk-form-actions {
  display: flex;
  gap: 8px;
  margin-top: 16px;
  flex-wrap: wrap;
}

/* ---------------- 划词菜单 ---------------- */

.bk-menu {
  position: fixed;
  z-index: 60;
  display: none;
  align-items: center;
  gap: 1px;
  padding: 5px 7px;
  border: 1px solid var(--bk-line-strong);
  border-radius: 12px;
  background: rgba(20, 27, 40, .97);
  box-shadow: 0 14px 40px rgba(4, 8, 14, .6);
  -webkit-backdrop-filter: blur(14px);
  backdrop-filter: blur(14px);
  transform: translate(-50%, 0);
  white-space: nowrap;
}
.bk-menu.is-on { display: flex; }
.bk-menu button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 30px;
  height: 30px;
  border: 0;
  border-radius: 8px;
  background: transparent;
  color: var(--bk-fg-dim);
  font-size: 14px;
  cursor: pointer;
  transition: background .14s ease, color .14s ease;
}
.bk-menu button:hover { background: var(--bk-tint-strong); color: var(--bk-stronger); }
.bk-menu-sep { width: 1px; height: 16px; margin: 0 4px; background: var(--bk-line); }
.bk-menu-colors { display: inline-flex; gap: 3px; margin-left: 4px; }
.bk-dot {
  width: 16px !important;
  height: 16px !important;
  margin: 0 1px;
  border-radius: 50% !important;
  background: var(--c) !important;
  box-shadow: inset 0 0 0 1px rgba(0, 0, 0, .22);
}
.bk-dot:hover { transform: scale(1.22); }

/* ---------------- 抽屉 / 浮层 ---------------- */

.bk-drawer,
.bk-helpbox {
  position: fixed;
  inset: 0;
  z-index: 70;
  display: grid;
  background: rgba(6, 10, 18, .62);
  -webkit-backdrop-filter: blur(5px);
  backdrop-filter: blur(5px);
  opacity: 0;
  visibility: hidden;
  transition: opacity .2s ease, visibility .2s ease;
}
.bk-drawer { place-items: stretch start; }
.bk-helpbox { place-items: center; }
.bk-drawer.is-on,
.bk-helpbox.is-on { opacity: 1; visibility: visible; }

.bk-drawer-panel {
  display: flex;
  flex-direction: column;
  width: min(88vw, 420px);
  height: 100%;
  border-right: 1px solid var(--bk-line-strong);
  background: var(--bk-bg-2);
  box-shadow: var(--bk-shadow);
  transform: translateX(-14px);
  transition: transform .24s ease;
}
.bk-drawer.is-on .bk-drawer-panel { transform: translateX(0); }

.bk-drawer-head,
.bk-helpbox-panel header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 16px;
  border-bottom: 1px solid var(--bk-line);
  flex: 0 0 auto;
}
.bk-drawer-head h3,
.bk-helpbox-panel h3 { margin: 0; color: var(--bk-stronger); font-size: 15px; }

.bk-lib-list {
  flex: 1 1 auto;
  overflow-y: auto;
  padding: 14px 16px;
}
.bk-lib-item {
  margin-bottom: 11px;
  padding: 12px 13px;
  border: 1px solid var(--bk-line);
  border-radius: 12px;
  background: var(--bk-tint);
}
.bk-lib-item.is-active { border-color: var(--bk-accent-2); background: var(--bk-tint-strong); }
.bk-lib-title {
  margin: 0 0 5px;
  color: var(--bk-stronger);
  font-size: 14px;
  font-weight: 700;
  line-height: 1.5;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.bk-lib-meta,
.bk-lib-time { margin: 0; color: var(--bk-fg-mute); font-size: 12px; line-height: 1.7; }
.bk-lib-pages { margin-left: 6px; }
.bk-lib-actions { display: flex; gap: 8px; margin-top: 10px; }

.bk-drawer-foot {
  padding: 12px 16px;
  border-top: 1px solid var(--bk-line);
  flex: 0 0 auto;
}

.bk-helpbox-panel {
  width: min(92vw, 620px);
  max-height: 84vh;
  display: flex;
  flex-direction: column;
  border: 1px solid var(--bk-line-strong);
  border-radius: 18px;
  background: var(--bk-bg-2);
  box-shadow: var(--bk-shadow);
  transform: translateY(10px) scale(.985);
  transition: transform .24s ease;
}
.bk-helpbox.is-on .bk-helpbox-panel { transform: translateY(0) scale(1); }
.bk-helpbox-panel ol {
  margin: 0;
  padding: 18px 22px 6px 40px;
  overflow-y: auto;
  color: var(--bk-fg);
  font-size: 13.5px;
  line-height: 1.9;
}
.bk-helpbox-panel li { margin-bottom: 11px; }
.bk-helpbox-panel b { color: var(--bk-stronger); }
.bk-helpbox-panel code {
  padding: 1px 6px;
  border-radius: 5px;
  background: var(--bk-tint-strong);
  color: #e6ecf5;
  font-size: 12.5px;
}
.bk-helpbox-note {
  margin: 0;
  padding: 12px 22px 18px;
  color: var(--bk-fg-mute);
  font-size: 12.5px;
  line-height: 1.8;
}

/* ---------------- 遮罩 / 提示 ---------------- */

.bk-busy {
  position: fixed;
  inset: 0;
  z-index: 90;
  display: grid;
  place-items: center;
  background: rgba(6, 10, 18, .5);
  opacity: 0;
  visibility: hidden;
  transition: opacity .18s ease, visibility .18s ease;
}
.bk-busy.is-on { opacity: 1; visibility: visible; }
.bk-busy-box {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 13px 22px;
  border: 1px solid var(--bk-line-strong);
  border-radius: 13px;
  background: rgba(20, 27, 40, .97);
  box-shadow: var(--bk-shadow);
  color: var(--bk-stronger);
  font-size: 13.5px;
}

.bk-toast {
  position: fixed;
  z-index: 95;
  bottom: 26px;
  left: 50%;
  max-width: min(90vw, 560px);
  padding: 11px 18px;
  border: 1px solid var(--bk-line-strong);
  border-radius: 12px;
  background: rgba(20, 27, 40, .97);
  box-shadow: var(--bk-shadow);
  color: var(--bk-stronger);
  font-size: 13.5px;
  line-height: 1.6;
  text-align: center;
  opacity: 0;
  visibility: hidden;
  transform: translate(-50%, 14px);
  transition: opacity .22s ease, transform .22s ease, visibility .22s;
}
.bk-toast.is-on { opacity: 1; visibility: visible; transform: translate(-50%, 0); }
.bk-toast[data-kind="warn"] { border-color: rgba(255, 214, 102, .62); }
.bk-toast[data-kind="error"] { border-color: rgba(255, 140, 140, .62); }

/* ---------------- 目录 / 搜索 浮层 ---------------- */

.bk-float {
  position: absolute;
  z-index: 30;
  top: 10px;
  display: none;
  flex-direction: column;
  width: min(84%, 340px);
  max-height: calc(100% - 20px);
  border: 1px solid var(--bk-line-strong);
  border-radius: 14px;
  background: rgba(20, 27, 40, .97);
  box-shadow: var(--bk-shadow);
  -webkit-backdrop-filter: blur(16px);
  backdrop-filter: blur(16px);
  overflow: hidden;
}
.bk-float.is-on { display: flex; }
.bk-float-left { left: 10px; }
.bk-float-right { right: 10px; }

.bk-float-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 10px 10px 14px;
  border-bottom: 1px solid var(--bk-line);
  flex: 0 0 auto;
}
.bk-float-head h3 { margin: 0; color: var(--bk-stronger); font-size: 13.5px; }

.bk-outline-list,
.bk-search-results {
  flex: 1 1 auto;
  overflow-y: auto;
  padding: 8px;
  min-height: 60px;
}

/* 目录项：按层级缩进 */
.bk-ol-item {
  display: flex;
  align-items: center;
  gap: 7px;
  width: 100%;
  padding: 6px 8px 6px calc(8px + var(--d, 0) * 14px);
  border: 0;
  border-radius: 8px;
  background: transparent;
  color: var(--bk-fg-dim);
  font: inherit;
  font-size: 13px;
  line-height: 1.5;
  text-align: left;
  cursor: pointer;
  transition: background .14s ease, color .14s ease;
}
.bk-ol-item i { flex: 0 0 auto; font-size: 11px; color: var(--bk-accent-2); }
.bk-ol-title {
  flex: 1 1 auto;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.bk-ol-page {
  flex: 0 0 auto;
  color: var(--bk-fg-mute);
  font-size: 11.5px;
  font-style: normal;
  font-variant-numeric: tabular-nums;
}
.bk-ol-item:hover { background: var(--bk-tint-hover); color: var(--bk-stronger); }
.bk-ol-item.is-on { background: var(--bk-tint-strong); color: var(--bk-stronger); }
.bk-ol-item.is-on i { color: var(--bk-amber); }

/* 搜索条 + 命中列表 */
.bk-search-bar {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 9px 10px;
  border-bottom: 1px solid var(--bk-line);
  flex: 0 0 auto;
}
.bk-search-bar input {
  flex: 1 1 auto;
  min-width: 0;
  height: 30px;
  padding: 0 10px;
  border: 1px solid var(--bk-line-strong);
  border-radius: 8px;
  outline: none;
  background: rgba(12, 18, 28, .6);
  color: var(--bk-stronger);
  font: inherit;
  font-size: 13px;
}
.bk-search-bar input:focus { border-color: var(--bk-line-strong); }
.bk-search-bar input::placeholder { color: var(--bk-fg-mute); }

.bk-hit {
  display: block;
  width: 100%;
  margin-bottom: 5px;
  padding: 7px 9px;
  border: 1px solid transparent;
  border-radius: 9px;
  background: var(--bk-tint);
  color: var(--bk-fg-dim);
  font: inherit;
  font-size: 12.5px;
  line-height: 1.6;
  text-align: left;
  cursor: pointer;
}
.bk-hit:hover { background: var(--bk-tint-hover); color: var(--bk-stronger); }
.bk-hit.is-on { border-color: var(--bk-amber); background: rgba(255, 214, 102, .12); color: var(--bk-stronger); }
.bk-hit-page {
  display: inline-block;
  margin-right: 6px;
  color: var(--bk-accent-2);
  font-weight: 700;
}
.bk-hit-text { word-break: break-word; }

.bk-hit.is-flash, .bk-hl.is-flash { animation: bkFlash 1s ease 2; }

/* ---------------- 工具栏：更多 / 快捷键面板 ---------------- */

.bk-toolbar-more {
  position: absolute;
  z-index: 30;
  top: 44px;
  right: 10px;
  display: none;
  width: min(88%, 340px);
  padding: 12px 14px;
  border: 1px solid var(--bk-line-strong);
  border-radius: 14px;
  background: rgba(20, 27, 40, .97);
  box-shadow: var(--bk-shadow);
  -webkit-backdrop-filter: blur(16px);
  backdrop-filter: blur(16px);
}
.bk-toolbar-more.is-on { display: block; }
.bk-more-title {
  margin: 0 0 8px;
  color: var(--bk-stronger);
  font-size: 12.5px;
  font-weight: 700;
}
.bk-keys {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 5px 12px;
  margin: 0;
  font-size: 12.5px;
}
.bk-keys dt {
  color: var(--bk-accent-2);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  white-space: nowrap;
}
.bk-keys dd { margin: 0; color: var(--bk-fg-mute); }
.bk-more-actions {
  display: flex;
  gap: 8px;
  margin-top: 12px;
  flex-wrap: wrap;
}

/* ---------------- 文献库进度 / 空态最近阅读 ---------------- */

.bk-lib-progress {
  height: 4px;
  margin: 8px 0 2px;
  border-radius: 3px;
  background: var(--bk-tint-strong);
  overflow: hidden;
}
.bk-lib-progress span {
  display: block;
  height: 100%;
  border-radius: 3px;
  background: linear-gradient(90deg, #7e96b8, #9db4d3);
}

.bk-recent {
  width: 100%;
  max-width: 620px;
  margin: 0 auto;
}
.bk-recent-item { background: var(--bk-tint); }

/* ---------------- 图区超清预览 ---------------- */

/* 框选模式的十字光标与禁止划词 */
.bk-scroller.is-region { cursor: crosshair; }
.bk-scroller.is-region .textLayer { pointer-events: none; }
.bk-scroller.is-region .bk-page { user-select: none; }

/* 拖拽时的选框（fixed 定位，避免跟随滚动容器偏移） */
.bk-marquee {
  position: fixed;
  z-index: 55;
  display: none;
  border: 1.5px dashed var(--bk-accent-2);
  border-radius: 4px;
  background: var(--bk-tint-strong);
  box-shadow: 0 0 0 1px var(--bk-line-strong) inset;
  pointer-events: none;
}
.bk-marquee.is-on { display: block; }

/* 自动识别出的图区热区：贴在 canvas-wrap 上，pointer-events 交给它自己 */
.bk-hotzone {
  position: absolute;
  z-index: 4;
  padding: 0;
  border: 1.5px solid rgba(126, 224, 192, .85);
  border-radius: 4px;
  background: rgba(126, 224, 192, .07);
  cursor: zoom-in;
  transition: background .15s ease, border-color .15s ease;
}
.bk-hotzone:hover,
.bk-hotzone:focus-visible {
  border-color: #7ee0c0;
  background: rgba(126, 224, 192, .2);
  outline: none;
}
.bk-hotzone-tag {
  position: absolute;
  top: 2px;
  left: 2px;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 2px 7px;
  border-radius: 6px;
  background: rgba(12, 18, 28, .82);
  color: #d8f6ec;
  font-size: 11px;
  line-height: 1.5;
  white-space: nowrap;
  pointer-events: none;
  opacity: 0;
  transition: opacity .15s ease;
}
.bk-hotzone:hover .bk-hotzone-tag,
.bk-hotzone:focus-visible .bk-hotzone-tag { opacity: 1; }

/* 浮层：整屏暗底 + 居中面板 */
.bk-region {
  position: fixed;
  inset: 0;
  z-index: 80;
  display: grid;
  place-items: center;
  background: rgba(6, 10, 18, .78);
  -webkit-backdrop-filter: blur(6px);
  backdrop-filter: blur(6px);
  opacity: 0;
  visibility: hidden;
  transition: opacity .18s ease, visibility .18s ease;
}
.bk-region.is-on { opacity: 1; visibility: visible; }

.bk-region-panel {
  display: flex;
  flex-direction: column;
  width: min(94vw, 1400px);
  height: min(92vh, 1000px);
  border: 1px solid var(--bk-line-strong);
  border-radius: 16px;
  background: var(--bk-bg-2);
  box-shadow: var(--bk-shadow);
  overflow: hidden;
}

.bk-region-head {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  padding: 10px 14px;
  border-bottom: 1px solid var(--bk-line);
  flex: 0 0 auto;
}
.bk-region-head h3 {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  margin: 0;
  color: var(--bk-stronger);
  font-size: 14px;
  white-space: nowrap;
}
.bk-region-head h3 i { color: var(--bk-accent-2); }
.bk-region-meta {
  flex: 1 1 auto;
  min-width: 0;
  margin: 0;
  color: var(--bk-fg-mute);
  font-size: 12px;
  line-height: 1.6;
  word-break: break-word;
}
.bk-region-tools {
  display: flex;
  align-items: center;
  gap: 6px;
  flex: 0 0 auto;
}
.bk-region-zoom {
  min-width: 46px;
  color: var(--bk-fg-dim);
  font-size: 12px;
  font-variant-numeric: tabular-nums;
  text-align: right;
}

/* 舞台：棋盘底（透明 PNG 也能看清），内部画布可平移缩放 */
.bk-region-stage {
  position: relative;
  flex: 1 1 auto;
  min-height: 0;
  display: grid;
  place-items: center;
  overflow: hidden;
  background-color: #1a2130;
  background-image:
    linear-gradient(45deg, var(--bk-tint) 25%, transparent 25%),
    linear-gradient(-45deg, var(--bk-tint) 25%, transparent 25%),
    linear-gradient(45deg, transparent 75%, var(--bk-tint) 75%),
    linear-gradient(-45deg, transparent 75%, var(--bk-tint) 75%);
  background-size: 22px 22px;
  background-position: 0 0, 0 11px, 11px -11px, -11px 0;
}
.bk-region-stage canvas {
  display: block;
  max-width: none;
  cursor: grab;
  box-shadow: 0 12px 40px rgba(0, 0, 0, .55);
  transform-origin: center center;
  will-change: transform;
}
.bk-region-stage canvas.is-panning { cursor: grabbing; }
.bk-region-empty {
  margin: 0;
  padding: 24px;
  color: var(--bk-fg-mute);
  font-size: 13px;
}

.bk-region-foot {
  flex: 0 0 auto;
  padding: 9px 14px;
  border-top: 1px solid var(--bk-line);
  color: var(--bk-fg-mute);
  font-size: 12px;
  line-height: 1.7;
}
.bk-region-foot strong { color: var(--bk-accent-2); }

/* ---------------- 响应式 ---------------- */

@media (max-width: 1180px) {
  .bk-page-body { --bk-right-w: 360px; }
}

@media (max-width: 900px) {
  .bk-page-body { --bk-topbar-h: 100px; }
  .bk-topbar {
    flex-wrap: wrap;
    height: auto;
    padding: 9px 12px;
    gap: 8px;
  }
  .bk-brand span { display: none; }
  .bk-open { order: 3; flex-basis: 100%; }
  .bk-topbar-right { order: 2; }
  .bk-topbar-right .bk-btn span { display: none; }
  .bk-topbar-right .bk-btn { padding: 0 10px; }

  .bk-workspace {
    grid-template-columns: minmax(0, 1fr);
    grid-template-rows: minmax(0, 1fr) minmax(0, 46vh);
  }
  .bk-workspace.is-collapsed {
    grid-template-columns: minmax(0, 1fr) 0px;
    grid-template-rows: minmax(0, 1fr) 0px;
  }
  .bk-right { border-left: 0; border-top: 1px solid var(--bk-line); }
  .bk-scroller { padding: 14px 12px 40px; }
  .bk-menu { transform: translate(-50%, 0) scale(.95); }

  /* 图区预览在小屏上要能在「图片」和「工具栏」之间分配高度 */
  .bk-region-panel {
    width: 100vw;
    height: 100vh;
    border-radius: 0;
    border: 0;
  }
  .bk-region-head { padding: 8px 10px; gap: 7px; }
  .bk-region-meta { flex-basis: 100%; order: 3; font-size: 11.5px; }
  .bk-region-tools { gap: 4px; }
  .bk-region-head .bk-btn span,
  .bk-region-head .bk-btn { font-size: 12px; }
  .bk-region-foot { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  .bk-page-body *,
  .bk-page-body *::before,
  .bk-page-body *::after {
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .01ms !important;
  }
  .bk-scroller { scroll-behavior: auto; }
}

/* 打印：只保留正文与笔记，方便直接存 PDF */
@media print {
  .bk-topbar, .bk-toolbar, .bk-menu, .bk-drawer, .bk-helpbox,
  .bk-busy, .bk-toast, .bk-pane-actions, .bk-toolbar-more,
  .bk-float, .bk-dropzone, .bk-recent, .bk-marquee, .bk-hotzone,
  .bk-region { display: none !important; }
  .bk-page-body { height: auto; overflow: visible; background: #fff; color: #000; }
  .bk-workspace { position: static; display: block; }
  .bk-left, .bk-right { border: 0; background: #fff; }
  .bk-scroller { overflow: visible; padding: 0; display: block; }
  .bk-page {
    box-shadow: none;
    border-radius: 0;
    break-inside: avoid;
    page-break-inside: avoid;
    /* 打印时用固定尺寸，避免骨架的像素宽高在不同纸型上跑偏 */
    width: var(--bk-page-w, auto) !important;
    height: var(--bk-page-h, auto) !important;
    margin: 0 auto 10px;
  }
}