Rated 5 out of 5 stars

This is a great add-on. But in this state it's currently broken because Mozilla changed their top level image css.
If the image is centered and one zooms in, the scrollbar is locked and you cannot scroll all the way up.

But there is a fix:
If one is to add this line

sheet += " img.overflowingVertical { margin-top: 0; }";

between line 98 and 99 in bootstrap.js, this would fix the issue.

I tried it locally and it seems to work, it would be great to see in the official version too, though.

Hope it helps.