JSFiddle - React, Tailwind, and code Playground

HTML

<div id = "master_wrapper">
<div id = "header">
	Header
</div>

CSS

body, html
{
	margin:0;
	height:100%;
}

#master_wrapper
{
	width:100px;
	height:100px;
	background:#57a957;
}

#header
{
    left:50%;
	width:50%;
	height:50%;
	background:red;
}