Update: The initial post mentioned transforms, which were used in the initial version, but later replaced by simple absolute positioning.
This sample uses CSS transitions, meaning that it requires a Firefox 4 preview build.
Webkit manages to do … something (Webkit tries to do some transitions in sequence instead of simultanously). Opera apparently has no support for pointer-events in HTML yet.
Try to disable the stylesheet (View/Page Style/No Style in Firefox): The document remains usable. Ugly, but usable.