z-index not properly rendered on iPad and Google Chrome 22
Just found out myself that the way that chrome 22+ handles z-index has been altered. Check out this awesome explanation here that I didn't write here...
http://updates.html5rocks.com/2012/09/Stacking-Changes-Coming-to-position-fixed-elements
Basically the way I understand it is that elements which have
position: fixed now get counted with their own z-index layer so you'll have to adjust your pages accordingly to suit.
Hope that helps!