JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/bootstrap/3.2.0/css/bootstrap.min.css">
<div class="container">
    <div class="btn-group">
        <button type="button" class="btn btn-primary btn-lg pad-left">Login</button>
        <button type="button" class="btn btn-primary btn-lg pad-left">Register</button>
    </div>
</div>

CSS

body, html {
    background-image: url('http://images.alphacoders.com/234/234641.jpg');
    background-size: cover;
    background-repeat: no-repeat;
    margin:0;
    padding:0;
    height: 100%;
}
.container {
    height: 100%;
    text-align: center;
    white-space: nowrap;
}
.container:before {
    content:"";
    display: inline-block;
    vertical-align: middle;
    width: 0;
    margin-right: -.25em;
    height: 100%;
}
.btn-group {
    display: inline-block;
    outline: 1px solid red;
    vertical-align: middle;
    white-space: normal;
	padding: 20px;
}