Very cool. The rule for class "book" is missing a border-radius as far as I can tell. Test: set color to e.g. pink, increase radius to maximum value, see that

Very cool. The rule for class "book" is missing a border-radius as far as I can tell. Test: set color to e.g. pink, increase radius to maximum value, see that the front image gets cropped but the pink area behind it is not. The backside of the book has a border-radius by the way. Edit: might be nice to only apply it to the right-hand side as the side with the spine is unlikely to have rounded corners.