JSFiddle - React, Tailwind, and code Playground

HTML

<div id="pop">
    pop
</div>
<div id="body">
    body<br>body<br>body<br>body<br>body<br>body<br>body<br>body<br>body<br>body<br>body<br>body<br>body<br>body<br>body<br>body<br>body<br>body<br>body<br>body<br>body<br>body<br>body<br>body<br>body<br>body<br>body<br>body
</div>

CSS

html,body{margin:0px;padding:0px;height:100%;overflow:hidden;}
#body{width:100%;height:100%;overflow:auto;}
#pop{position:fixed;top:0px;left:0px;right:0px;bottom:0px;overflow:auto;opacity:0.5;background:#fff;}