It looks like you're new here. If you want to get involved, click one of these buttons!
No problem and again hate to be a nag, but bad news, I just updated and both white boxes are still there (screenshot below):
As you can see, those 2 white elements are specific to books which is why I did not previously see/report them and maybe why you haven't seen them since paper books popularity has kinda sunk these days. :)
At a real quick f12 glance it almost looks like at least one (if not both) are actually within iframes which is a bit different than their other elements I've been looking at.