JSFiddle - React, Tailwind, and code Playground

HTML

<div class="parent">
    <span class="child">I'm vertically/horizontally centered!</span>
</div>

CSS

.parent {
    height: 200px;
    width: 50px;
    background: lightgray;
    text-align: center;
}
.parent > .child {
    line-height: 200px;
}