User blog comment:DaNASCAT/Technical Update: August 3, 2011/@comment-3080486-20110805061346/@comment-3450419-20110806053006

I don't think there's a pure CSS solution since .WikiHeader is replaced by .AdminDashboardHeader, but if you really don't like it showing everywhere, putting this in personal CSS hides everything admin-dashboard related and makes Special:RecentChanges as wide as it used to be.

/* Hide AdminDashboard */ .WikiaArticle.AdminDashboardChromedArticle, .WikiaArticle.expanded { width: 982px; } .AdminDashboard, .AdminDashboardDrawer, .AdminDashboardGeneralHeader.AdminDashboardArticleHeader, .AdminDashboardNavigation, .AdminDashboardHeader, .AdminDashboardRail, .AdminDashboardTabs { display: none; } .WikiaArticle { background: transparent; }

I think you can use JS to add back the missing .WikiHeader but I don't know anything about that code :/ so maybe someone else can help you with that.