See the discussion in that bug. The mechanism that the settings app uses for transitions is a bit fragile, and was broken by bug 703241.

Agreed, we need another way to do these panel transitions — not only because of the viewport trick, but also because the transitions are really sketchy, see bug 796804. Yesterday I spent most of my day trying to get smoother transitions, which will probably imply some JS to set a `display: none;' rule on all panels but the active and former active one… If you have any suggestion to make these transitions more robust *and* smoother, I’m all ears. I’d prefer to stay on a purely declarative solution, but the priority is to get smooth/robust transitions here.

(In reply to Fabien Cazenave [:kaze] from comment #1) > Yesterday I spent most of my day trying to get smoother transitions, which > will probably imply some JS to set a `display: none;' rule on all panels but > the active and former active one… If you are transitioning something from hidden, transition the |visibility| property instead of setting |display| before or after the transition. This is what I recently learned on the job, and I've even wrote a blog post about it! http://blog.timc.idv.tw/posts/css-transition-on-visibility-property/

With the recent work and AMD refactor this seems to be working fairly well now. Please reopen with more details if you think this is still an issue.