Given the sad state of the CSS Validator, and the desire for a uniform interface
to these two functions, it would be great to enable the Validator to parse and
Validate CSS.

It might be done by writing a Parser from scratch -- using either Chapter 4 of
CSS21 or the CSS3 Syntax module -- or by creating a SGML Application for CSS.

The CSS syntax is generic and checking it might be compared to XML's
"well-formedness" checking, with further checking akin to XML's "Valid" concept.
The generic syntax is also not particularly large or complex, and the number of
selectors, properties, etc. in CSS is far less overwhelming when considered in
the context of a validator/parser then when considering implementing a renderer
or applying the stylesheet to a web page.

With a modular parser backend for the Validator, having CSS be one of the
avilable parsers seems both appropriate and, not the least, actually _doable_.