JSFiddle - React, Tailwind, and code Playground

HTML

<div class="poop">
    <div class="inner"/>
</div>

CSS

.poop{
    height:400px;
    width:400px;
    background-color:red;
    position: relative;
}
.inner{
    background-color:green;
    position: absolute;
    height:50%;
    width:50%;
    margin:auto;
    left: 0;
    right: 0;
    top: 0;
    bottom: 0;
}