Is this the best approach? Preview component master solution with grid

At the beginning I was a little confuse about what was the better approach to solve this. Actually, still I don't know if my solution is completely correct, but at least it works.

I made the HTML and CSS part very quickly. Where I had to think a little bit harder were with the JavaScript part. Which is funny because I took a path where most of the the job is using CSS.

Also, I still can't figure out how to make it work the fadeOut keyframe animation. If you have any suggestion about my solution I would be thankful.