JSFiddle - React, Tailwind, and code Playground

HTML

<div id="kolo"></div>

CSS

#kolo
{
    height:300px;
    width:300px;
    background-color:yellow;
    border:3px solid black;
    border-radius:20px 20px;
    opacity:0.1;
}

JavaScript

$(document).ready(function(){
        $("#kolo").animate({ opacity: "1" }, 50000);
 });