JSFiddle - React, Tailwind, and code Playground

HTML

<a href="#">
    <img src="http://teststranek.kvalitne.cz/images/obrazek-1.jpg" height="240" width="320">
    <img class=drudy src="http://teststranek.kvalitne.cz/images/99ccff-ff6666.png" height="240" width="320">
</a>

CSS

a img {
    border: 2px solid red;
    float: left;
    margin-right: -364px;
}
a img.drudy {
    border: 2px solid blue;
    -moz-transition: opacity 0.5s; /* Firefox 4 */
    -webkit-transition: opacity 0.5s; /* Safari and Chrome */
    -o-transition: opacity 0.5s;
    transition: opacity 0.5s; } /* CSS3? */
a:hover img.drudy {
    filter: alpha(opacity=0); /* IE */
    opacity: 0;
}