"position: fixed" div is not fixed when parent rotates or translates

Question

A div with "position: fixed" is embedded into a parent div. When the parent rotates or translates, the child div moves also.

Is it a bug? I expected the child div to remain fixed.

HTML snippet:

 <div id="mask">
    <div id="page">
    </div>
 </div>

See a repro at: http://jsfiddle.net/PseKK/

I know that I can fix it by applying the reverse transformation to the child div but for performance reasons in my real scenario, I am looking for a solution that doesn't involve extra-transformation.

Any idea how to overcome?

Solution

This is a repost, the answer is located in this original question

Positions fixed doesn't work when using -webkit-transform

Unfortunately it is a bug, but there seems to be a way to get around it.

Comments

[viebel]

Thanks a lot! Do you know how to 'making the transformed div an image and using it as the background' as they suggest?

[JimmyBanks]

I believe they are saying is that instead of using CSS for your transformed div, use an image, and place it as the background within a fixed div, so you will have an image placed, instead of actual CSS for the transform shape. [Unfortunately thats not really a "fix", but sounds like there's nothing else to do.]

[vsync]

what do you mean "there seems to be a way to get around it" ? why can't you just write it as an answer if there is a way, instead or posting a comment as an answer?

[Alkanshel]

The background image fix that answer proposes is a very niche solution.. clearly not applicable to all instances of a fixed element with a transitioned parent.

[mesqueeb]

You should edit the answer and write what the way around it there is......