JSFiddle - React, Tailwind, and code Playground

HTML

<div id="main">
</div>
<div style="width: 200px; background-color: #999; z-index: 10; position: fixed; right: 20px; top: 300px; height: 83px;">
</div>

CSS

#main{
    height:900px;
    width:100px;
    background-color:blue;
}