RE: [css3-2d-transforms][css3-images] <position> grammar is duplicated or points to the wrong spec

David:
> I think calc() should not have any discontinuities, i.e., putting
> "calc()" around a valid value shouldn't change its behavior, and
> putting a "+1px" inside a calc() should move change the result by
> 1px.

As it currently stands, calc() does not have discontinuities regarding this.

More specifically...

Example A:
	width: 200px;
	background-position: calc(10%);
Example B:
	width: 200px;
	background-position: calc(10% + 1px);

The left edge of the image for Example A is at offset 20px.  For Example B, it's 21px.  No discontinuity.


David:
> It's not at all changing the behavior of a property -- it's keeping
> that property's behavior as it always has been, since CSS1 in 1996.

Prior to your proposal for calc() behavior, CSS has never had support for "% + offset" in a background-position dimension.  What am I missing?