JSFiddle - React, Tailwind, and code Playground

by isochronous

HTML

<div id="primary">
    <div id="secondary">
        Blah
    </div>
</div>

CSS

#primary {
    background-color: #000;
    width: 640;
    height: 480;
}

#secondary {
    background-color: #f00;
    width: 320;
    height: 240;
    position: relative;
    left: 50%;
    top: 50%;
    margin-left: -160px;
    margin-top: -120px;
}