User blog comment:Dopp/Technical Update: November 29, 2011/@comment-1474707-20111130124459/@comment-3030984-20111130133702

Odd. I see it fine on w:c:casualty. Checking Firebug on that wiki shows that the white background is part of the default editor css. However, on 24 and beekeeping, the grey color if part of the default code. Must be the light/dark varients.