Why doesn't scrolling of the loaded part of the site work in Google Chrome and Opera?

Question

css

Good day! I had a certain problem:
the scrollbar does not work correctly in Opera (version 34.0.2036.50) and Google Chrome browsers when you load (enlarge) an image on the site birjis.ru/gallery/portret . It turns out that after this action, a part of the html code is loaded, which goes beyond the screen visibility area, and the browser does not scroll the page all the way down (crops it). And in Firefox everything works stably.
After reviewing the styles of the elements, I didn’t find anything suspicious, I tried to put the focus on the loading element - it didn’t help either.
I suppose it will not be written very well from the technical side, but I ask you to help me understand this situation. Screenshot from Opera

Screenshot from Firefox