[css3-page] Making z-index support non-optional on page-margin boxes.

Hi,

 From css3-page §4.1 (emphasis added):
> The UA **may** support the z-index property for page-margin boxes.

In appendix A:
> The following CSS 2.1 [CSS21] properties apply to page-margin boxes.
> If a conforming user agents supports any of these properties on block
> boxes, then it must also support that property for page-margin boxes
> **(except for z-index, which is optional for page-margin boxes)**.


I don’t see a reason for having optional features. I suggest making the 
z-index support non-optional:

* Remove the "(except for z-index, which is optional for page-margin 
boxes)" part of Appendix A.

* Use in §4.1 a wording similar to Appendix A: "If a conforming user 
agent supports the 'z-index' property on positioned elements, then it 
most also support that property on page-margin boxes."

Not supporting z-index on elements already makes an UA non-conforming to 
CSS 2.1, AFAICT.

-- 
Simon Sapin

Received on Sunday, 24 February 2013 10:50:38 UTC