@namespace a url(http://www.example.org/a);
div.stub > p {color : red }
div.stub > a|* { color : red ; display : block ; margin-bottom : 1em }
div.stub *|*:not([test="1"]) { color : lime }

<div class="stub">
<q xmlns="http://www.example.org/a" test="1">
  <r test="11">This text should be</r>
  <r>in green characters</r>
</q>
<s xmlns="http://www.example.org/a">This text should be in green characters</s>
<p>This text should be in green characters</p>
</div>