JSFiddle - React, Tailwind, and code Playground

HTML

<div id="abc">
</div>

CSS

#abc{
   width: 500px;
   height: 200px;
   background-color: red;   
}
.a{
   width: 200px;
   height: 100px;
   margin-left: auto;
   margin-right: auto;
   background-color: blue;   
}

JavaScript

var parent = document.getElementById('abc'),
    ele = document.createElement('div');

ele.setAttribute('class', 'a');
ele.innerHTML = "Some other contents here";
parent.appendChild(ele);