JSFiddle - React, Tailwind, and code Playground

HTML

<div>center center box</div>

CSS

body, html { width: 100%; height: 100%; margin: 0; }
div {
    width:50px;
    height:50px;
    background:orange;
    position:relative;
    top: 50%;
    -ms-transform: translateY(-50%);
    -webkit-transform: translateY(-50%);
    transform: translateY(-50%);
    left: 50%;
    -ms-transform: translateX(-50%);
    -webkit-transform: translateX(-50%);
    transform: translateX(-50%);
    display:block;
}