How to change the scrollbar colors of TWebBrowser?

{A page must be already loaded into TWebBrowser}

procedure TForm1.Button1Click(Sender: TObject);
begin
 with WebBrowser1 do
 begin
   OleObject.document.body.Style.scrollbarArrowColor := '#0099FF';
   OleObject.document.body.Style.scrollbar3DLIGHTCOLOR := '#FFFFFF';
   OleObject.document.body.Style.scrollbarDarkShadowColor := '#0099FF';
   OleObject.document.body.Style.scrollbarFaceColor := '#99CCFF';
   OleObject.document.body.Style.scrollbarHighlightColor := '#0099FF';
   OleObject.Document.body.Style.scrollbarShadowColor := '#0099FF';
   OleObject.Document.body.Style.scrollbarTrackColor := '#FFFFFF';
 end;
end;