JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    <div></div>
 </div>

CSS

*{
    margin: 0;
}
html,body{
 height:100%;
 }
 div{
 min-height:20%;
    background: #f00;
 }
div>div{
    background: #0f0;
}