Okay. Can you try this approach for now? 1. UniServerModule -> CustomCSS: .customTreeView .x-grid-item { background-color: initial; } 2. procedure TMainForm.UniFormCreate(Sender: TObject); begin with UniTreeView1, UniTreeView1.JSInterface do begin JSConfig('cls', ['customTreeView']); JSConfig('bodyStyle', ['background-color:' + uniColor2Web(Color)]); end; end; 3. Uses ... , UniGUIJSUtils;