procedure TMainForm.UniBitBtn1Click(Sender: TObject); var vPosition: Integer; begin vPosition := 75; with UniBitBtn1.JSInterface do begin JSCall('btnWrap.setStyle', ['background-image', 'linear-gradient(to right, green, lime)']); JSCall('btnWrap.setStyle', ['background-size', vPosition.ToString + '% 100%']); JSCall('btnWrap.setStyle', ['background-repeat', 'no-repeat']); end; end;