<!DOCTYPE html>
<div style="position:absolute; height: 200px; width: 200px; background: lightgray"></div>
<div style="position:absolute; height: 200px; width: 200px; top: 50px; left: 50px; background:lightblue"></div>
<div id="target" style="position:absolute; height: 200px; width: 200px; top: 50px; left: 50px; background:lightblue"></div>