libcss selection question

[Paul]

Hi all!

How can a user of libcss distinguish between these two situations: a) 
property was defined using a default value in CSS and b) property was 
undefined in CSS for the node. Those are different because in a latter 
case the value of that property should be taken from a node attribute 
(in my case of svg styling). As far as I can tell, for a root node, the 
property is always initialised using the default value, so when 
composing a style I can't distinguish between a and b.

Thanks,

Paul