JSFiddle - React, Tailwind, and code Playground

HTML

<div class="main">
    <div class="sub"><h2>I am center</h2></div>
</div>

CSS

.main{
    width:1200px;
    height:1200px;
    display:table;
    text-align:center;
    margin-right: auto;

margin-left: auto;
}

.sub{
    vertical-align:middle;
    display:table-cell;
    
}

JavaScript

$(function () {
    scrollTo((($(document).width() - $(window).width()) / 2),(($(document).height() - $(window).height()) / 2));
});