I built a ribbon box with a parallax effect here: http://method.ac.
If you look at the corners of the subscribe box in IE9, you will see that they don’t behave as expected, they are jumping from their mirrored state (via ms-transform: scale(-1, 1) to normal, but only some times. It works fine in Opera, Firefox, Safari and Chrome.
I’m changing the height on scroll with jquery.
The background is an svg. I can’t use four different images because webkit has a bug where it doesn’t render the svg if viewBox is set to 0 0 1 1 and the black triangle is on the upper left corner (go figure).
Any help is greatly appreciated.
Since the bug seems to be related to the svg, perhaps you should go about making those corners by a different method. I propose border art. The CSS would be something like:
I believe this should help keep everything cross browser including your IE9 issue.