requesting clip-rule help

Hi all,

I'm working on the WebPlatformDocs CSS clip-rule
property<http://docs.webplatform.org/wiki/css/properties/clip-rule>article
and am having trouble developing a working HTML/CSS example.

The W3C spec <http://dev.w3.org/fxtf/masking/#the-clip-rule> shows SVG code
in its examples, but I can't get similar code to work in a test page, and
don't know if SVG is even the right angle (pun intended).

I'd appreciate some help if anyone is interested; let me know, and I can
provide more details and code.

Thanks,
Dave Gash