JSFiddle - React, Tailwind, and code Playground

HTML

<div class="outer"><div class="inner"></div></div>

CSS

.outer {
    background: url(http://www.gravatar.com/avatar/ac7d698503da0da779de67116e3b4c31?s=32&d=identicon&r=PG);
    height: 32px; width: 32px;
}
.inner {
    background: url(http://www.gravatar.com/avatar/e9739ec5574d9977b522d1c80fb8de84?s=32&d=identicon&r=PG);
    opacity: 1;
    -moz-transition: opacity 0.3s; -webkit-transition: opacity 0.3s; -o-transition: opacity 0.3s; transition: opacity 0.3s; 
    height: 32px; width: 32px;
}
.inner:hover {
    opacity: 0;
}