JSFiddle - React, Tailwind, and code Playground

HTML

<div class="parent">
    <div class="child">Some content</div>
</div>

CSS

.parent {
    background-color: #ccc;
    width: 200px;
    height: 200px;
    position: relative;
}

.child {
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    margin: auto;
    background-color: #888;
    color: #fff;
    width: 100px;
    height: 100px;
}