uses mshtml;

procedure TForm1.WBDocumentComplete(Sender: TObject; 
const pDisp: IDispatch; var URL: OleVariant);
var
  Doc : IHTMLDocument2;
  Element : IHTMLElement;
begin
  Doc := IHTMLDocument2(TWebBrowser(Sender).Document);
  if Doc = nil then
    Exit;
  Element := Doc.body;
  if Element = nil then
    Exit;
  case Make_Flat of
    TRUE : Element.style.borderStyle := 'none';
    FALSE : Element.style.borderStyle := '';
  end;
end;