I agree that this probably means that web elements that are 'flat' would be styled by CSS with a depth. This is important if other material presented to the user really is stereo (e.g. a left/right eye coded movie). The movie will be set so that the eyes are expected to have a certain 'convergence' (i.e. they are looking slightly inward towards some point) and it's important that if material is overlaid on that. it has the same convergence. Obviously, this is unlike the real world where focus distance and convergence distance are the same (focus distance is fixed at the screen distance), but the brain can get very confused if two things that are both in focus are at difference convergence distances.
This is not a simple question, as I expect you are beginning to realize. David Singer Multimedia and Software Standards, Apple Inc.
