Validation failures with css

[armplinker]

I have been using a program named CSE Html Validator to check my HTML5 and css for correctness. It blows chunks on anything in the css referring to MadCap e.g. mc-heading-level: 0;

It appears that other css validators also have issues with this. I would vastly prefer to simply put a namespace reference at the top of my css and keep moving rather than all the hijinks others have used to get around this.

I cannot seem to locate a css namespace reference to put at the top of my css so that the validator can resolve these madcap directives and not complain. There is some comment that a particular xsd is inserted at the top of every output css by Flare but that url used as a namespace directive inside my css file does not work.

Does anybody have the correct url for that?