QyLeVO

index.html

<div class="show thumb">
<img class="thumb" src="http://api.arcivr.com/api/events/PUV6EF/posts/6573/media/thumb">
<img class="media" src="http://api.arcivr.com/api/events/PUV6EF/posts/6573/media/media">
</div>

QyLeVO.markdown

QyLeVO

A Pen by Captain Anonymous on CodePen.

License.

script.js

$(document).ready(function () {
  setInterval(function() {
    $('.show').toggleClass('thumb media')
  }, 1000);
});

scripts

<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>

style.css

img {
  display: none;
  width: 100%;
}

.show.thumb .thumb, .show.media .media {
  display: block;
}