<!doctype HTML>
<iframe srcdoc="
<!doctype HTML>
<style>
  div {
    background: linear-gradient(lightblue, yellow);
    background-size: 300px 300px;
    background-position: 50px 50px;
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
  }
</style>
<div></div>"></iframe>
