JSFiddle - React, Tailwind, and code Playground

HTML

<div id="shadow"> </div>
<div id="under"> </div>

CSS

#shadow {
    background-color: #35BFFF;
    height: 300px;
    width: 100px;
    -moz-box-shadow: 0px 0px 11px rgba(0,0,0,1);
    -webkit-box-shadow: 0px 0px 11px rgba(0,0,0,1);
    box-shadow: 0px 0px 11px rgba(0,0,0,1);
    float: left;
    z-index: 999;
    position: relative;
}
#under {
    float: left;
    height: 300px;
    width: 100px;
    background-color: red;
    position: relative;
}