@namespace url();
   @namespace ns url();
   test { background: red; display: block; padding: 1em; }
   stub ~ [ns|attribute^=start]:not([ns|attribute~=mid])[ns|attribute*=dle][ns|attribute$=end] ~ test [ { background: lime; }

 <div>

  <script>
   <![CDATA[

    function test() {
      document.getElementsByTagNameNS('', 'test')[1].setAttributeNS('', 'attribute', 'start middle end');
    }

    window.setTimeout(test, 100);
   ]]>
  </script>

  <p> The following block should be green. </p>

  <!-- root of selector -->
  <stub xmlns=""></stub>

  <!-- middle part of selector does not match this -->
  <test xmlns="" xmlns:none="" none:attribute="fake"></test>

  <!-- middle part of selector matches this once attribute is fixed -->
  <test xmlns="" xmlns:none="" none:attribute="start mid dle end"></test>

  <!-- subject of selector -->
  <test xmlns=""></test>

 </div>