<div style="position:relative; width:420px; border:2px solid black; height:200px">
<div style="opacity:0.5;position:relative">
<div style="height:200px;background-color:green;position:absolute;width:200px;left:0;top:0"></div>
<div style="height:200px;background-color:green;position:absolute;width:200px;right:0;top:0"></div>
<div style="position:absolute;height:98px;width:98px;background-color:lightgray; left:160px; top:50px;background-color:green;border:1px solid lime">
</div>
</div>
</div>
</div>