[css-backgrounds-3] # in value notation undefined because ref is to CSS2

[gsnedders]

Section two states:

This specification follows the CSS property definition conventions from [CSS2].

And, e.g., background-repeat's value is defined as <repeat-style># .

However, CSS2's property definition value doesn't define #.

Presumably the fix is to simply refer to CSS Values and Units.

[fantasai]

Need to create some standardized boilerplate to propagate out, but this should be sufficient for css-backgrounds-3 for now.