<style>
* {
  image-rendering: pixelated;
}
</style>
<script>
window.requestIdleCallback(() => {
  a.setSelectionRange(-1, 1)
  document.head.innerHTML = undefined
})
</script>
<embed src="data:image/gif;base64,R0lGODlhAQABAAD/ACwAAAAAAQABAAACADs="></embed>
<textarea id="a">aaaaaaaaaaaaaaaa</textarea>
<script>
  const embed = document.querySelector("embed");
  embed.onload = function() {
    var countdown = 20;
    if (location.search) {
        countdown = parseInt(location.search.slice(1)) - 1;
	  }

    if (countdown > 0) {
      location.search = countdown;
    } else {
      window.parent.postMessage("done", "*");
    }
  }
</script>
