JSFiddle - React, Tailwind, and code Playground

HTML

<div class="center">Div content</div>

CSS

.center {
    font-family:sans-serif;
    width:300px;
    height:300px;
    border:1px solid green;
    margin: 0 auto;
    text-align:center;
}

JavaScript

$().ready(function () {
    $(".center").css("margin-top", ($(window).height() - 300) / 2);
});