JSFiddle - React, Tailwind, and code Playground

HTML

<div id="div1">This is content in #div1</div>

CSS

#div1 {
    display: none;
    width: 250px;
    height: 250px;
    background: #ff0000;
    padding:10px;
    color: #ffffff;

JavaScript

$( document ).ready(function() {
  $("#div1").fadeIn(5000);
});