JSFiddle - React, Tailwind, and code Playground

HTML

<div id="parent">
    <div id="child">
    </div>
</div>

CSS

#parent {
    background-color: yellow;
    width: 300px;
    height: 200px;
    margin: 50px;
    
    position: relative;
}

#child {
    background-color: green;
    width: 50px;
    height: 50px;
    
    position: absolute;
    top: 20px;
    left: 30px;
}