JSFiddle - React, Tailwind, and code Playground

HTML

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

</div>

CSS

html, body, .container {
    height: 100%;
}
{ extra braces...
.container {
    display: -webkit-flexbox;
    display: -ms-flexbox;
    display: -webkit-flex;
    display: flex;
    -webkit-flex-align: center;
    -ms-flex-align: center;
    -webkit-align-items: center;
    align-items: center;
    justify-content: center;
}
/* ...act as comment? */ }