@namespace a url(http://www.example.org/a);
@namespace b url(http://www.example.org/b);
@namespace html url(http://www.w3.org/1999/xhtml);
*|p, *|q, *|r, *|s { display : block ; margin-bottom : 1em }
*|p.deu, *|q { background-color : lime ! important }
div.stub html|*:not([*|class~="deux"]),
   div.stub *|*:not(html|*):not([*|foo~="deux"]) { background-color : red }