JSFiddle - React, Tailwind, and code Playground

HTML

<div id='happy'><img src='http://baby.esdlife.com/uploads/2008/12/mrhappy.jpg' style='width:300px; height:300px;'></img>
</div>

CSS

#happy { 
    margin:30px 10px;
    position:relative; /*must be relative */
}

#happy:hover:after { /*on hover after image do this... */
    content:"";
    position:absolute; /* must be absolute */
    display:block;
    width:300px; /* must set width */
    height:300px; /* must set height */ 
    background:url('http://www.hellobloggerz.com/wp-content/uploads/2012/12/happy-readers.jpg');
    z-index:2;
    top:0;
}