JSFiddle - React, Tailwind, and code Playground

HTML

This is a normal tekst, blahblahblah.

<div id="fade"></div>
<div id="overlay">Fake Popup</div>

CSS

#fade {
    opacity:.80;
    -moz-opacity:0.8;
    filter: alpha(opacity=80);
    -ms-filter:"progid:DXImageTransform.Microsoft.Alpha(Opacity=80)";

    display: none;
    position: absolute;
    top: 0%;
    left: 0%;
    width: 100%;
    height: 100%;
    background-color: #000;
    z-index:1001;
}

#overlay {
 text-align: left;
    display: none;
    position: absolute;
    top: 50%;
    left: 50%;
    border: 3px solid #000;
    background-color: #fff;
    z-index:1002;
    overflow: hidden;
    color: #cc3333;
    padding: 10px;
}

JavaScript

$("#fade").show("fade", 5000);
$("#overlay").show();