JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    <div>Hello there</div>
</div>

CSS

html, body {
    width: 100%;
    height: 100%;
}

body > div {
    width: 90%;
    height: 90%;
    background: green;
}

body > div > div {
    width: 100%;
    background: red;
}