JSFiddle - React, Tailwind, and code Playground

HTML

<div id="content"><div id="inner"></div></div>

CSS

#content {
    display: block;
    width: 100px;
    height: 100px;
    background: red
}
#inner {
    height: 20px;
    width: 20px;
    display: block;
    background: green;
    margin: 0 auto;
    z-index: 2
    position: relative
}