JSFiddle - React, Tailwind, and code Playground

HTML

<div id='my_div'>
    <div class="centered">this is vertically centered</div>
</div>

CSS

body, html
{
    height: 100%;
}
body
{
    margin: 0;
    padding: 0;
    border: 1px solid blue;
}
#my_div
{
    width: 300px;
    height: 200px;
    border: 1px solid red;
    margin-left: auto;
    margin-right: auto;
    height: 100%;
    display: table;
    overflow: hidden;
}
.centered
{
    display: table-cell;
    vertical-align: middle;
    text-align: center;
}