title: How to negate conjunction of two attributes in CSS selector
body: <p>I wonder how to build a CSS selector to match element that do not have two given attributes at the same time. I tried </p>
  
  <pre><code>tagName:not([attra][attrb])
  </code></pre>
  
  <p>As I want all <code>tagName</code>s that does <code>:not</code> have <code>[attra]</code> <strong>and</strong> <code>[attrb]</code> <strong>at the same time</strong>.</p>
  
  <p>Unfortunately Firefox, and Chrome (stable and Canary) says that</p>
  
  <pre><code>'tagName:not([attra][attrb])' is not a valid selector.
  </code></pre>
  
  <p>While <code>tagName[attra][attrb]</code>, <code>tagName:not([attra]):not([attrb])</code> are valid, but naturally does not return what I want.</p>