function adjustFrameSize() {
  const frame = frameElement// as HTMLIFrameElement;
  if (frame) {
    frame.width  = getDocWidth()  + 'px';
    frame.height = '0px'; // FF workaround to force scrollHeight recalculation!
    frame.height = getDocHeight() + 'px';
  }
}

function getDocWidth() {
  return Math.max(
    document.body.scrollWidth, document.documentElement.scrollWidth,
    document.body.offsetWidth, document.documentElement.offsetWidth,
    document.body.clientWidth, document.documentElement.clientWidth
  );
}

function getDocHeight() {
  return Math.max(
    document.body.scrollHeight, document.documentElement.scrollHeight,
    document.body.offsetHeight, document.documentElement.offsetHeight,
    document.body.clientHeight, document.documentElement.clientHeight
  );
}