I looked at your listings and spotted the problem. You are using a Horizontal (side-by-side) grouping of the book images that forces the template wide to accomodate them in two of the listings. Notice how that didn't happen with the grouping Slideshow on the third listing Glorious Refrains.
I'd recommend grouping Paired or you might try my favorite (for books) the Thumbnail. Check this antiquarian listing of mine recently completed for Thumbnail example (hover mouse over Thumbnails in the listing)

Mont-Saint-Michel and Chartres
Danno
Oh...and that's an Auctiva template I used.