/* === CSS Reset & Variables === */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}

:root {
  --header-h: 42px;
  --toolbar-h: 28px;
  --sidebar-w: 280px;
  --bg: #f5f5f5;
  --bg-sidebar: #fff;
  --bg-header: #4a6fa5;
  --bg-header-active: #3d5d8a;
  --bg-tree-selected: #e8f0fe;
  --border: #d0d0d0;
  --text: #333;
  --text-light: #666;
  --text-header: #fff;
  --text-header-active: #ffd54f;
  --accent: #1a73e8;
  --radius: 4px;
  --shadow: 0 1px 3px rgba(0,0,0,0.12);
  --transition: 0.2s ease;
}

/* === Layout === */
html, body { height: 100%; overflow: hidden; font-family: "Microsoft YaHei", "Segoe UI", Tahoma, sans-serif; font-size: 13px; color: var(--text); background: var(--bg); }

#app {
  display: grid;
  grid-template-rows: var(--header-h) 1fr;
  grid-template-columns: var(--sidebar-w) 1fr;
  grid-template-areas: "header header" "sidebar content";
  height: 100vh;
}

/* === Header === */
#header {
  grid-area: header;
  background: var(--bg-header);
  display: flex;
  align-items: center;
  padding: 0 8px;
  gap: 2px;
  z-index: 10;
  box-shadow: var(--shadow);
}
#header .tabs { display: flex; gap: 2px; height: 100%; align-items: flex-end; }
#header .tab {
  padding: 6px 16px;
  border-radius: var(--radius) var(--radius) 0 0;
  cursor: pointer;
  color: rgba(255,255,255,0.8);
  font-size: 13px;
  font-weight: 500;
  transition: var(--transition);
  border: none;
  background: transparent;
  white-space: nowrap;
}
#header .tab:hover { color: #fff; background: rgba(255,255,255,0.1); }
#header .tab.active { color: var(--text-header-active); background: var(--bg-header-active); font-weight: bold; }
#header .header-right { margin-left: auto; display: flex; align-items: center; gap: 8px; }
#header .title { color: #fff; font-size: 14px; font-weight: bold; margin-right: 8px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; max-width: 300px; }
#btnPrint, #btnToggleSidebar {
  background: none; border: 1px solid rgba(255,255,255,0.3); color: #fff;
  padding: 4px 12px; border-radius: var(--radius); cursor: pointer;
  font-size: 12px; transition: var(--transition);
}
#btnPrint:hover, #btnToggleSidebar:hover { background: rgba(255,255,255,0.15); }

/* === Sidebar === */
#sidebar {
  grid-area: sidebar;
  background: var(--bg-sidebar);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  position: relative;
}
#sidebar.collapsed { display: none; }
#sidebar-toolbar {
  display: flex;
  align-items: center;
  gap: 2px;
  padding: 4px 6px;
  background: #f0f0f0;
  border-bottom: 1px solid var(--border);
  min-height: var(--toolbar-h);
}
#sidebar-toolbar button {
  background: #fff;
  border: 1px solid #ccc;
  border-radius: 3px;
  padding: 2px 10px;
  cursor: pointer;
  font-size: 11px;
  color: var(--text);
  transition: var(--transition);
}
#sidebar-toolbar button:hover { background: #e8e8e8; border-color: #aaa; }

.sidebar-panel { flex: 1; overflow: hidden; display: flex; flex-direction: column; }
.sidebar-panel.hidden { display: none; }

/* === Tree Panel === */
#treePanel { overflow-y: auto; padding: 4px 0; }
.tree-node { white-space: nowrap; user-select: none; }
.tree-node .node-row {
  display: flex; align-items: center; height: 22px; cursor: pointer; padding: 0 4px;
  transition: background var(--transition);
}
.tree-node .node-row:hover { background: #f0f0f0; }
.tree-node .node-row.selected { background: var(--bg-tree-selected); }
.tree-node .node-row.selected .node-label { color: var(--accent); font-weight: 500; }
.tree-node .toggle-icon {
  width: 16px; height: 16px; display: inline-flex; align-items: center; justify-content: center;
  flex-shrink: 0; cursor: pointer; transition: transform var(--transition);
}
.tree-node .toggle-icon svg { width: 12px; height: 12px; fill: #666; }
.tree-node .toggle-icon.expanded svg { transform: rotate(90deg); }
.tree-node .toggle-icon.placeholder { visibility: hidden; }
.tree-node .node-icon { width: 16px; height: 16px; flex-shrink: 0; margin: 0 1px; display: flex; align-items: center; justify-content: center; }
.tree-node .node-icon svg { width: 14px; height: 14px; }
.tree-node .node-icon.folder svg { fill: #e6a817; }
.tree-node .node-icon.file svg { fill: #5a7ab0; }
.tree-node .node-label { margin-left: 2px; font-size: 12px; overflow: hidden; text-overflow: ellipsis; }
.tree-children { overflow: hidden; }
.tree-children.collapsed { display: none; }

/* === Index Panel === */
#indexPanel { padding: 8px; }
#indexPanel input { width: 100%; padding: 6px 8px; border: 1px solid var(--border); border-radius: var(--radius); font-size: 12px; margin-bottom: 6px; }
#indexPanel input:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 2px rgba(26,115,232,.2); }
#indexPanel select { flex: 1; width: 100%; border: 1px solid var(--border); border-radius: var(--radius); font-size: 12px; padding: 4px; }
#indexPanel .idx-btn-row { display: flex; justify-content: flex-end; margin-top: 6px; }
#indexPanel .idx-btn-row button { padding: 4px 14px; border: 1px solid #ccc; background: #fff; border-radius: 3px; cursor: pointer; font-size: 12px; }
#indexPanel .idx-btn-row button:hover { background: #e8e8e8; }

/* === Search Panel === */
#searchPanel { padding: 8px; overflow-y: auto; }
#searchPanel .search-input { width: 100%; padding: 6px 8px; border: 1px solid var(--border); border-radius: var(--radius); font-size: 12px; margin-bottom: 6px; }
#searchPanel .search-input:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 2px rgba(26,115,232,.2); }
#searchPanel .search-options { display: flex; gap: 12px; margin-bottom: 6px; font-size: 12px; }
#searchPanel .search-options label { display: flex; align-items: center; gap: 4px; cursor: pointer; }
#searchPanel .search-btn-row { display: flex; gap: 6px; margin-bottom: 6px; }
#searchPanel .search-btn-row button { padding: 4px 14px; border: 1px solid #ccc; background: #fff; border-radius: 3px; cursor: pointer; font-size: 12px; }
#searchPanel .search-btn-row button.primary { background: var(--accent); color: #fff; border-color: var(--accent); }
#searchPanel .search-btn-row button:hover { background: #e8e8e8; }
#searchPanel .search-btn-row button.primary:hover { background: #1557b0; }
#searchPanel .search-results { flex: 1; width: 100%; border: 1px solid var(--border); border-radius: var(--radius); font-size: 12px; padding: 2px; overflow-y: auto; min-height: 200px; }

/* === Bookmark Panel === */
#bookmarkPanel { padding: 8px; }
#bookmarkPanel select { width: 100%; border: 1px solid var(--border); border-radius: var(--radius); font-size: 12px; padding: 2px; flex: 1; }
#bookmarkPanel .bm-info-row { margin: 6px 0; }
#bookmarkPanel .bm-info-row input { width: 100%; padding: 4px 6px; border: 1px solid var(--border); border-radius: 3px; font-size: 12px; background: #f9f9f9; }
#bookmarkPanel .bm-btn-row { display: flex; gap: 6px; }
#bookmarkPanel .bm-btn-row button { padding: 4px 14px; border: 1px solid #ccc; background: #fff; border-radius: 3px; cursor: pointer; font-size: 12px; flex: 1; }
#bookmarkPanel .bm-btn-row button:hover { background: #e8e8e8; }
#bookmarkPanel .bm-label { font-size: 11px; color: var(--text-light); margin-bottom: 2px; }

/* === Content Area === */
#contentArea {
  grid-area: content;
  background: #fff;
  overflow: hidden;
}
#contentFrame {
  width: 100%;
  height: 100%;
  border: none;
}

/* === Responsive === */
@media (max-width: 768px) {
  #app { grid-template-columns: 1fr; }
  #sidebar { position: fixed; left: 0; top: var(--header-h); bottom: 0; width: var(--sidebar-w); z-index: 100; box-shadow: 2px 0 8px rgba(0,0,0,0.2); }
  #sidebar.collapsed { display: none; }
  #header .title { display: none; }
  #contentArea { grid-column: 1; }
}

/* === Scrollbar === */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: #ccc; border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: #aaa; }

/* === Loading === */
#loading-overlay {
  position: fixed; top: 0; left: 0; right: 0; bottom: 0;
  background: #fff; z-index: 9999; display: flex;
  align-items: center; justify-content: center; font-size: 14px; color: #666;
}
#loading-overlay.done { display: none; }

/* === Resize handle === */
#resize-handle {
  position: absolute; right: -3px; top: 0; bottom: 0; width: 6px;
  cursor: col-resize; z-index: 5; background: transparent;
}
#resize-handle:hover, #resize-handle.active { background: rgba(26,115,232,.2); }