JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    <div></div>
</div>

CSS

body {
    margin: 0;
    width: 100%;
    height: 100%;
}
body > div {
    width: 200px;
    height: 200px;
    background: #ff0;
    position: relative;
}
body > div > div {
    width: 10%;
    height: 10%;
    -webkit-transform: translateY(-50%);
    background: #f00;
    position: absolute;
    top: 50%;
}