JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <div id="page-login">
        <div class="panel">Some content</div>
    </div>
</div>

CSS

html, body {
    min-height:100%;
    height:100%;
}

.container {
	display: table;
    height:100%;
	width:100%;
	background:#303030;
}

#page-login {
    display: table-cell;
    vertical-align: middle
}

.panel {
    height: 100px;
    background-color: #fff;
}