JSFiddle - React, Tailwind, and code Playground

HTML

<div id='my_div'></div>

CSS

html, body {height: 100%}
body {
    margin: 0;
    padding: 0;
    border: 1px solid blue;
}
#my_div {
    width: 300px;
    height: 200px;
    position: absolute;
    top: 50%; left: 50%;
    margin: -100px 0 0 -150px;
    border: 1px solid red;
}