Thumbnail size on playlist

I’m using audio playlists on a page and have thumbnails set for the audio items in the playlist. What I’d like to do is either make the thumbnails bigger (wider actually) so they’re like a banner at the top of the playlist, or be able to actually create a banner at the top of the playlist area and not use thumbnails at all.

Any ideas? Thanks in advance.

If you’re wanting to visualize, look here:

http://www.sunnyslopemc.org/music-testbed/

Click on “Come Now is the Time to Worship” and you’ll see the little square thumbnail. I’d like to use all that horizontal real estate right there.