Why does this 3D CSS overlap instead of clip?

Question

Why do these 3D CSS planes overlap in Firefox and Chrome and not in Safari?

http://jsfiddle.net/yNfQX/6/

..and how do I make it behave like safari?

Safari & Firefox Preview

Answer 1

Looks like a bug... from https://bugzilla.mozilla.org/show_bug.cgi?id=689498:

Bug 689498 - Intersecting planes are not z-ordered properly

Alistair MacDonald 2012-04-12 12:22:25 PDT Safari & Mobile Safari no longer have this problem. The problem still exists in Chrome and Firefox.

Broken: Firefox 14.0a1 (2012-04-12) -Win7 Broken: Chrome 20.0.1096.1 -Win7 Fixed : Safari 5.1.5 (75.34.55.3) -Win7 Fixed : Mobile Safari (last updated over a month ago) -iOs

Link to test-case and screen-grabs: http://f1lt3r.com/code/3d-css-transforms-intersecting-planes-not-clipping/