CSS3 Selectors - :root

Hi,

I have just discovered what I believe to be a bug with the way the :root 
pseudo class has been implemented.

The specification states the following about this pseudo-class selector:
/
"The :root pseudo-class represents an element that is the root of the 
document. In HTML 4, this is always the HTML element."/

What it does not describe is where the :root can be used, from what I 
have tried, it only works when used at the beginning of a selector.

/":root p.test { color: red; }"/

However the following does not work:

/"p.test :root body { background: red; }"/

Am i missing something here or is this something that has not yet been 
addressed? I was hoping to be able to use the :root pseudo class to 
adjust styled based on whether or not an element can be found within the 
document.

Regards,
Karl Brightman
@karlbright
karl@karlbright.org