JSFiddle - React, Tailwind, and code Playground

HTML

<div id="outer">
    <div id="inner">
        content
    </div>
</div>

CSS

#outer {
    position: relative;
}
#inner {
    position: absolute;
    left: 10%;
    right: 10%;
    top: 10%;
    bottom: 10%;
}

html, body { height: 100%; }
#outer {
    background-color: purple;
    width: 50%;
    height: 50%;
}
#inner {
    background-color: yellow;
}