/* v6.4 DEV1E · hierarchical question navigation */
.v64-subject-empty{border:1px dashed #d5dce5;border-radius:10px;padding:18px 16px;display:grid;gap:4px;text-align:center;background:#fafbfc;color:#667386}
.v64-subject-empty b{font-size:14px;color:#344256}
.v64-subject-empty span{font-size:11px;color:#8792a1}
.v64-builder.v64-no-subject>:scope{}.v64-builder.v64-no-subject>.v64-step,.v64-builder.v64-no-subject>.v64-publish{display:none!important}
.v64-builder.v64-flat-subject .v64-chips[data-group="sub"],.v64-builder.v64-flat-subject .v64-step-actions{display:none!important}
.v64-builder.v64-flat-subject .v64-flat-combo-section{grid-template-columns:1fr!important}
.v64-builder.v64-flat-subject .v64-flat-combo-section>b{display:none!important}
.v64-builder.v64-flat-subject .v64-qmeta>b:first-child{display:none!important}

.v64-tree-nav{display:grid!important;gap:6px!important;align-content:start!important;overflow:auto!important}
.v64-tree-nav>.v64-tree-all{width:100%!important;display:flex!important;align-items:center!important;justify-content:space-between!important;gap:8px!important;border:1px solid #d8e1eb!important;background:#fff!important;border-radius:8px!important;padding:8px 9px!important;color:#475569!important;font-size:11px!important;font-weight:800!important}
.v64-tree-nav>.v64-tree-all::before{content:'一级';font-size:9px;font-weight:800;color:#8b97a7;background:#eef2f6;border-radius:5px;padding:2px 5px;margin-right:2px}
.v64-tree-nav>.v64-tree-all.on{background:#eaf2fb!important;border-color:#9dbddd!important;color:#24527d!important}
.v64-tree-nav>section{display:grid!important;gap:4px!important;border-top:1px solid #e4e9ef!important;border-left:0!important;padding:6px 0 0!important}
.v64-tree-parent{width:100%;border:0;background:transparent;border-radius:7px;padding:7px 8px;display:grid;grid-template-columns:minmax(0,1fr) auto auto;align-items:center;gap:7px;text-align:left;color:#475569;cursor:pointer}
.v64-tree-parent:hover{background:#eef2f6}
.v64-tree-parent>span:first-child{display:flex;align-items:center;gap:6px;min-width:0}
.v64-tree-parent small{font-size:9px;font-weight:800;color:#8b97a7;background:#eef2f6;border-radius:5px;padding:2px 5px;flex:0 0 auto}
.v64-tree-parent b{font-size:11px;color:#344256;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.v64-tree-parent-meta{font-size:9px;color:#94a0ae;white-space:nowrap}
.v64-tree-parent i{font-style:normal;color:#8793a3;transition:transform .16s ease}
.v64-tree-nav>section.open>.v64-tree-parent{background:#f5f8fb}
.v64-tree-nav>section.open>.v64-tree-parent i{transform:rotate(180deg)}
.v64-tree-children{display:none;gap:3px;padding-left:12px}
.v64-tree-nav>section.open>.v64-tree-children{display:grid}
.v64-tree-child{width:100%!important;display:grid!important;grid-template-columns:auto minmax(0,1fr) auto!important;align-items:center!important;justify-content:initial!important;gap:6px!important;border:0!important;background:transparent!important;border-radius:7px!important;padding:6px 8px!important;text-align:left!important;color:#5b6879!important;font-size:10px!important;font-weight:700!important;white-space:normal!important}
.v64-tree-child::before{content:'二级';font-size:8px;font-weight:800;color:#9aa5b3;background:#f1f4f7;border-radius:5px;padding:2px 4px}
.v64-tree-child:hover{background:#f1f4f7!important}
.v64-tree-child.on{background:#e7f0fa!important;color:#24527d!important}
.v64-tree-child span{justify-self:end;font-size:9px!important;color:#8f9baa!important}
.v64-tree-flat{display:grid!important;gap:3px!important;border-top:1px solid #e4e9ef!important;padding-top:6px!important}
.v64-tree-flat>.v64-tree-flat-type{display:grid!important}
.v64-tree-flat>.v64-tree-flat-type::before{content:'题型'}
.v64-tree-flat-mode>.v64-tree-all::before{content:'全部'}
.v64-level3{display:flex;align-items:center;gap:8px;min-height:28px;border-bottom:1px solid #e7ebf0;padding:0 1px 7px}
.v64-level3 strong{font-size:11px;color:#344256}
.v64-level3 span{font-size:10px;color:#7d8998;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}

@media(max-width:760px){
  .v64-browser-layout{grid-template-columns:1fr!important;gap:8px!important}
  .v64-tree-nav{max-height:none!important;overflow:visible!important;display:grid!important;padding:7px!important;border-radius:9px!important}
  .v64-tree-nav>section{display:grid!important;padding:6px 0 0!important;border-left:0!important;border-top:1px solid #e4e9ef!important}
  .v64-tree-nav>section>.v64-tree-parent{display:grid!important;width:100%!important}
  .v64-tree-children{display:none!important;padding-left:8px!important}
  .v64-tree-nav>section.open>.v64-tree-children{display:grid!important}
  .v64-tree-child{width:100%!important;white-space:normal!important;flex:initial!important}
  .v64-tree-flat>.v64-tree-flat-type{display:grid!important}
  .v64-question-scroll{max-height:520px!important}
}
@media(max-width:430px){
  .v64-tree-nav{padding:6px!important}
  .v64-tree-parent{padding:7px 6px}
  .v64-tree-child{padding:6px!important}
  .v64-level3{align-items:flex-start;flex-direction:column;gap:2px}
  .v64-level3 span{white-space:normal}
}
@media(prefers-color-scheme:dark){
  .v64-subject-empty{background:#111827;border-color:#334155;color:#94a3b8}.v64-subject-empty b{color:#e5e7eb}.v64-subject-empty span{color:#94a3b8}
  .v64-tree-nav>.v64-tree-all,.v64-tree-parent,.v64-tree-child{color:#cbd5e1!important}
  .v64-tree-nav>.v64-tree-all{background:#0f172a!important;border-color:#334155!important}
  .v64-tree-nav>.v64-tree-all.on,.v64-tree-child.on{background:#12304a!important;color:#dbeafe!important}
  .v64-tree-parent:hover,.v64-tree-nav>section.open>.v64-tree-parent,.v64-tree-child:hover{background:#172033!important}
  .v64-tree-parent b,.v64-level3 strong{color:#e5e7eb}
  .v64-tree-parent small,.v64-tree-child::before{background:#172033;color:#94a3b8}
  .v64-tree-nav>section,.v64-level3,.v64-tree-flat{border-color:#334155!important}
  .v64-level3 span,.v64-tree-parent-meta{color:#94a3b8}
}