JSFiddle - React, Tailwind, and code Playground

HTML

<body>
    <ul>
      <li class="leaf"><img src="http://avatarmaker.net/free-avatars/avatars/animated_214/sleepy_cat_animated_avatar_100x100_29622.gif"></li>
      <li class="leafhidden"><img></li>
      <li class="leafhidden"><img></li>
    </ul>
</body>

CSS

.leaf img:hover {
    content:url('http://rookery.s3.amazonaws.com/941000/941430_96b2_625x1000.jpg');
}