JSFiddle - React, Tailwind, and code Playground

by Softlink

HTML

<div id="main">
        <div id="elem"></div>
    </div>

CSS

html, body{
    height: 200%;
}    

#main { position: absolute; width: 400px; height: 200px; background: #ccc;}
#elem { background: red; height: 100px; position: fixed; top: 300px; width: 100px; }