JSFiddle - React, Tailwind, and code Playground

HTML

<div id="big">
    <div id="small"></div>
</div>

CSS

#big {
    width: 600px;
    height: 800px;
    background: green;
    position: relative;
}
#small {
    background: red;
    width: 200px;
    height: 200px;
    position: absolute;
    bottom: 0; left: 200px;
}