.settings-category:hover .settings-submenu {
      display: block;
    }


    .settings-option {
      padding: 9px 12px;
      font-size: 13px;
      cursor: pointer;
      user-select: none;
    }

    .settings-option:hover {
      background: var(--bg2);
    }

    .settings-option.active {
      font-weight: 600;
    }


    #font-size-slider {
      -webkit-appearance: none;
      appearance: none;
      width: 100%;
      height: 4px;
      border-radius: 2px;
      background: var(--border);
      outline: none;
      cursor: pointer;
    }

    #font-size-slider::-webkit-slider-thumb {
      -webkit-appearance: none;
      appearance: none;
      width: 14px;
      height: 14px;
      border-radius: 50%;
      background: var(--accent);
      cursor: pointer;
      border: 2px solid var(--bg);
      box-shadow: 0 1px 3px rgba(0,0,0,0.18);
    }

    #font-size-slider::-moz-range-thumb {
      width: 14px;
      height: 14px;
      border-radius: 50%;
      background: var(--accent);
      cursor: pointer;
      border: 2px solid var(--bg);
      box-shadow: 0 1px 3px rgba(0,0,0,0.18);
    }


    #status-bar {
      padding: 10px 16px;
      border-top: 1px solid var(--border);
      font-size: 12px;
      color: var(--text2);
      display: flex;
      align-items: center;
      gap: 6px;
    }


    .status-dot {
      width: 7px;
      height: 7px;
      border-radius: 50%;
      background: var(--danger);
      flex-shrink: 0;
    }

    .status-dot.connected { background: var(--status-connected); }


    #main {
      flex: 1;
      display: flex;
      flex-direction: column;
      min-width: 0;
      min-height: 0;
      overflow: hidden;
    }


    #main-shell {
      flex: 1;
      display: flex;
      min-width: 0;
      min-height: 0;
    }


    #chat-panel {
      flex: 1;
      display: flex;
      flex-direction: column;
      min-width: 0;
      min-height: 0;
    }


    #chat-header {
      padding: 14px 20px;
      border-bottom: 1px solid var(--border);
      background: var(--chat-header-bg);
      display: flex;
      align-items: center;
      justify-content: flex-start;
      gap: 12px;
      flex-shrink: 0;
    }


    #chat-title {
      font-size: 14px;
      font-weight: 500;
      color: var(--text2);
      overflow: hidden;
      text-overflow: ellipsis;
      white-space: nowrap;
      flex: 1;
    }


    #token-display {
      font-size: 12px;
      color: var(--text2);
      white-space: nowrap;
      display: none;
      line-height: 1;
      padding: 4px 8px;
      border-radius: 6px;
      margin-right: 8px;
      transition: background 0.3s;
    }


    #chat-actions {
      display: flex;
      align-items: center;
      gap: 8px;
      flex-shrink: 0;
    }


    .header-icon-btn {
      width: 36px;
      height: 36px;
      border-radius: 8px;
      border: 1px solid transparent;
      background: transparent;
      color: var(--text2);
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      flex-shrink: 0;
      transition: border-color 0.15s, background 0.15s;
    }

    .header-icon-btn svg { width: 20px; height: 20px; fill: none; stroke: currentColor; stroke-width: 1.5; }

    .header-icon-btn:hover {
      border-color: var(--border);
      background: var(--bg2);
    }


    #compact-btn,
    .toolbar-select {
      height: 28px;
      border: 1px solid var(--border);
      background: var(--image-btn-bg);
      color: var(--text2);
      border-radius: 999px;
      padding: 0 10px;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 6px;
      font-size: 12px;
      white-space: nowrap;
    }

    #compact-btn:hover:not(:disabled),
    .toolbar-select:hover,
    .toolbar-select:focus {
      border-color: var(--border-strong);
      background: var(--bg2);
      color: var(--text2);
    }

    .toolbar-select {
      padding: 0 10px;
      outline: none;
    }

    .toolbar-select {
      min-width: 104px;
      appearance: none;
      -webkit-appearance: none;
      -moz-appearance: none;
      cursor: pointer;
      padding-right: 26px;
      background-image:
        linear-gradient(45deg, transparent 50%, var(--text2) 50%),
        linear-gradient(135deg, var(--text2) 50%, transparent 50%);
      background-position:
        calc(100% - 14px) 11px,
        calc(100% - 9px) 11px;
      background-size: 5px 5px, 5px 5px;
      background-repeat: no-repeat;
    }

    #compact-btn:disabled { opacity: 0.45; cursor: not-allowed; }


    #doc-rail-resize {
      width: 6px;
      cursor: col-resize;
      flex: 0 0 6px;
      position: relative;
      background: linear-gradient(to right, transparent 0, transparent 2px, var(--resize-divider) 2px, var(--resize-divider) 4px, transparent 4px);
    }

    #doc-rail-resize:hover,
    #doc-rail-resize.dragging {
      background: linear-gradient(to right, transparent 0, transparent 2px, var(--accent) 2px, var(--accent) 4px, transparent 4px);
    }


    #action-rail {
      width: 380px;
      min-width: 280px;
      max-width: 1000px;
      background: var(--bg);
      display: flex;
      flex-direction: column;
      align-items: stretch;
      padding: 0;
      gap: 0;
      flex-shrink: 0;
      min-height: 0;
    }


    .rail-actions {
      display: flex;
      flex-direction: row;
      gap: 8px;
      flex-shrink: 0;
      background: var(--bg2);
      padding: 14px 10px;
      border-bottom: 1px solid var(--border);
    }

    .rail-btn-icon svg {
      width: 16px;
      height: 16px;
      display: block;
      stroke: currentColor;
      fill: none;
      stroke-width: 1.8;
      stroke-linecap: round;
      stroke-linejoin: round;
    }


    #doc-browser {
      min-height: 0;
      display: flex;
      flex-direction: column;
      gap: 10px;
      flex: 1;
      padding: 4px;
    }


    #doc-columns {
      min-height: 0;
      display: grid;
      grid-template-columns: repeat(2, minmax(0, 1fr));
      gap: 0;
      flex: 0 0 28%;
      border: 1px solid var(--border);
      border-radius: 12px;
      background: var(--bg2);
      overflow: hidden;
    }


    .doc-column {
      min-width: 0;
      min-height: 0;
      border: none;
      border-right: 1px solid var(--border);
      border-radius: 0;
      background: transparent;
      display: flex;
      flex-direction: column;
      overflow: hidden;
    }

    .doc-column:last-child {
      border-right: none;
    }


    .doc-column-header {
      min-height: 36px;
      border-bottom: 1px solid rgba(185, 173, 143, 0.35);
      padding: 8px 10px;
      display: flex;
      align-items: center;
      gap: 8px;
      color: var(--text2);
      font-size: 12px;
      font-weight: 650;
      flex-shrink: 0;
    }


    .doc-column-title {
      min-width: 0;
      overflow: hidden;
      text-overflow: ellipsis;
      white-space: nowrap;
    }


    .doc-back-btn {
      border: none;
      background: transparent;
      color: var(--text2);
      cursor: pointer;
      font-size: 12px;
      padding: 0;
      opacity: 0.9;
    }

    .doc-back-btn:disabled {
      opacity: 0.35;
      cursor: default;
    }


    .doc-column-body {
      flex: 1;
      min-height: 0;
      overflow-y: auto;
      padding: 6px;
      display: flex;
      flex-direction: column;
      gap: 4px;
    }

    .doc-entry {
      border: none;
      border-bottom: 1px solid var(--border);
      background: transparent;
      color: var(--text2);
      padding: 8px 10px;
      border-radius: 0;
      text-align: left;
      cursor: pointer;
      font-size: 12px;
      display: flex;
      align-items: center;
      gap: 6px;
      min-width: 0;
      width: 100%;
    }

    .doc-entry:last-child {
      border-bottom: none;
    }

    .doc-entry:hover {
      color: var(--text);
      background: rgba(255, 255, 255, 0.4);
    }

    .doc-entry.active {
      background: rgba(255, 255, 255, 0.55);
      color: var(--text);
      font-weight: 500;
      box-shadow: inset 3px 0 0 var(--accent);
    }

    .doc-entry-label {
      min-width: 0;
      overflow: hidden;
      text-overflow: ellipsis;
      white-space: nowrap;
    }


    #doc-root-tabs {
      display: flex;
      flex-shrink: 0;
      gap: 6px;
      padding: 6px 8px;
      border: 1px solid var(--border);
      border-radius: 12px;
      background: var(--bg2);
    }

    .doc-root-tab {
      flex: 0 1 auto;
      min-width: 0;
      border: none;
      border-radius: 8px;
      background: transparent;
      color: var(--text2);
      cursor: pointer;
      font-size: 12px;
      font-weight: 500;
      padding: 5px 8px;
      display: flex;
      align-items: center;
      gap: 5px;
    }

    .doc-root-tab:hover {
      color: var(--text);
      background: rgba(255, 255, 255, 0.4);
    }

    .doc-root-tab.active {
      color: var(--text);
      background: rgba(255, 255, 255, 0.55);
      box-shadow: inset 3px 0 0 var(--accent);
    }

    .doc-root-tab-icon {
      width: 14px;
      height: 14px;
      flex-shrink: 0;
    }

    .doc-root-tab-label {
      min-width: 0;
      overflow: hidden;
      text-overflow: ellipsis;
      white-space: nowrap;
    }


    #doc-tabs {
      display: flex;
      align-items: center;
      gap: 4px;
      flex: 0 0 auto;
      min-height: 36px;
      max-width: 100%;
      padding: 4px 8px;
      overflow-x: auto;
      overflow-y: hidden;
      border-bottom: 1px solid var(--border);
      scrollbar-width: thin;
    }

    .doc-tab {
      display: flex;
      align-items: center;
      gap: 5px;
      min-width: 0;
      max-width: 180px;
      flex-shrink: 0;
      border: 1px solid var(--border);
      border-radius: 8px;
      background: transparent;
      color: var(--text2);
      cursor: pointer;
      font-size: 12px;
      padding: 4px 8px;
      white-space: nowrap;
    }

    .doc-tab:hover {
      color: var(--text);
      background: rgba(255, 255, 255, 0.4);
    }

    .doc-tab.active {
      color: var(--text);
      background: rgba(255, 255, 255, 0.55);
      font-weight: 500;
      box-shadow: inset 3px 0 0 var(--accent);
    }

    .doc-tab.editing .doc-tab-icon {
      color: var(--accent);
    }

    .doc-tab.temporary {
      font-style: italic;
    }

    .doc-tab-icon {
      width: 14px;
      height: 14px;
      flex-shrink: 0;
    }

    .doc-tab-label {
      min-width: 0;
      overflow: hidden;
      text-overflow: ellipsis;
      white-space: nowrap;
      /* 斜体字形向右倾斜，预留少量空间避免尾部被裁切/贴近关闭按钮 */
      padding-right: 3px;
    }

    .doc-tab-close {
      display: inline-flex;
      flex: 0 0 auto;
      align-items: center;
      justify-content: center;
      width: 16px;
      height: 16px;
      border-radius: 6px;
      color: var(--muted);
      font-size: 0;
      line-height: 1;
    }

    .doc-tab-close:hover {
      background: rgba(255, 0, 0, 0.12);
      color: #c0392b;
    }

    .doc-tab-close-icon {
      width: 12px;
      height: 12px;
    }


    .doc-empty {
      padding: 10px;
      font-size: 12px;
      color: var(--muted);
    }


    #doc-vertical-resizer {
      height: 6px;
      cursor: row-resize;
      flex-shrink: 0;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    #doc-vertical-resizer::after {
      content: "";
      width: 64px;
      height: 3px;
      border-radius: 2px;
      background: var(--border);
      opacity: 0.6;
    }

    #doc-vertical-resizer:hover::after {
      opacity: 1;
      background: var(--border-strong);
    }


    #doc-preview-panel {
      border: 1px solid var(--border);
      border-radius: 12px;
      background: var(--bg2);
      display: flex;
      flex-direction: column;
      min-height: 0;
      flex: 1 1 64%;
      overflow: hidden;
    }


    #doc-preview-toolbar {
      border-bottom: 1px solid rgba(185, 173, 143, 0.35);
      padding: 10px 12px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 10px;
      flex-shrink: 0;
    }


    #doc-selection-status {
      min-width: 0;
      flex: 1;
      display: flex;
      flex-direction: row;
      align-items: center;
      gap: 12px;
    }


    .doc-selection-lines {
      font-size: 12px;
      color: var(--text2);
      white-space: nowrap;
      overflow: hidden;
      text-overflow: ellipsis;
      flex-shrink: 0;
    }


    .doc-selection-summary {
      font-size: 12px;
      color: var(--muted);
      min-width: 0;
      overflow: hidden;
      text-overflow: ellipsis;
      white-space: nowrap;
    }


    .doc-toolbar-actions {
      display: flex;
      align-items: center;
      gap: 8px;
      flex-shrink: 0;
    }


    #doc-refresh-btn,
    #doc-edit-btn {
      border: 1px solid var(--border);
      background: var(--image-btn-bg);
      color: var(--text2);
      border-radius: 999px;
      padding: 0 12px;
      height: 30px;
      cursor: pointer;
      flex-shrink: 0;
    }