JSFiddle - React, Tailwind, and code Playground

HTML

<div id="item">to be centered</div>

CSS

#item {
    height:400px;
    width:700px;
    background-color:red;
    -webkit-border-radius: 10px;
    -moz-border-radius: 10px;
    border-radius: 10px;
    text-align: center;
vertical-align: middle;
line-height: 400px;
}