You do not have to edit the CSS of user-submitted pages to remove stuff you don't like; you can do what I did instead. I don't like the narrower content or sidebar ads either, although I used
Stylish to remove them from all pages (and force the content to use the
full width of the window), and to remove script warnings, as well as to
remove the "fineprint" area (used for editing the page) from printouts (this also means I now have to maintain my own stylesheets, although I can deal with this; furthermore my stylesheets won't affect anyone else since they are local to my computer). However, I cannot figure out how to make the printout to use the full width of the page, nor to convert pictures to monochrome on the printout (if you know how to do these things, please tell me). However, note that at least Firefox does have "responsive design mode" which allows to test it at various screen sizes, as well as rotation and touch events (I myself do not use it, although it can be useful to you if you do mobile and that stuff).
