<!DOCTYPE html>
<div style="position:relative; width:1px; height:1px; background:orange;">
  <div style="position:absolute; left:450px; top:450px; width:100px; height:100px; background:blue;"></div>
  <div style="position:absolute; left:400px; top:400px; width:100px; height:100px; background:yellow;"></div>
</div>