User blog comment:Susanolivia/Fixed Width, Sidebar, and the Removal of Monaco/@comment-189311-20101001134741/@comment-4713673-20101001210040

Monobook is a legacy option that we no longer completely support, which means that certain features used in that skin are sometimes broken or don't work as they should. For that reason, and because it is legacy and not the present, we only offer it as a personal option and not a default on a wiki.