Note that transform-style: preserve-3d creates stacking context and containing block.

Author: smfr

css-transforms/ChangeLog

@@ -1,3 +1,6 @@
+2015-1-29 Simon Fraser <simon.fraser@apple.com>
+    Note that transform-style: preserve-3d creates stacking context and containing block.
+    
 2014-10-31 Dirk Schulze <dschulze@adobe.com>
     Introduce 'transform-box' property to specify the reference
     boxes: 'border-box', 'fill-box' and 'view-box'.