User blog comment:Rupert Giles/Layout Changes: Breakpoints and Typography/@comment-2040889-20150519232318/@comment-7700555-20150519234224

The specific examples include the large amount of white space on my screen, about one third, the larger font, the compressed content area, and so on.

So basically, in my opinion, the fix would be to undo this update. Hopefully that too comes soon.