<!DOCTYPE HTML>
<style>
body {
background-color: green;
}
#thediv {
width: 300px;
height: 100px;
position: absolute;
top: 20px;
left: 20px;
box-shadow: 3px 3px 2px rgba(255,0,0,0.6);
</style>
<div id="thediv"></div>