JSFiddle - React, Tailwind, and code Playground

HTML

<div id = "mainDiv">
    <div id="childDiv"></div>
</div>

CSS

#mainDiv{
    height:300px;
    width:300px;
    background : yellow;
    position: relative;
    display: table-cell;
    vertical-align: middle;
    text-align: center;
}

#childDiv{
    height:100px;
    width:100px;
    background : red;
    display: inline-block;
}