JSFiddle - React, Tailwind, and code Playground

HTML

<button id="altunel">vamos!</button>

CSS

body, html {
    height: 100%;
}
body {
    background-image: url(http://2.bp.blogspot.com/-HTwSvAcLA50/UR1YrS4v9eI/AAAAAAAAD9E/6_Vr5bwX8GQ/s1600/TUNEL.jpg);
    background-size: 100%;
    background-position: center;
    background-repeat: no-repeat;
    background-color: black;
}
body.go {
    background-size: 6000%;
    transition: all 2s ease-in
}

button {
    font-size: 2em;
    padding: 20px;
}

JavaScript

document.getElementById('altunel').onclick = function () {
    document.getElementsByTagName('body')[0].className = 'go'
}