title: CSS multiple :not doesn't work as expected
body: <p>I have the follow code:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>a {
      color: black
  }
  
  a:not(.test1) {
      color: red
  }
  
  a:not(.test1):not(.test2) {
      color: green;
  }
  
  a.test {
      color: blue
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;a class='test'&gt;
      TEST
  &lt;/a&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>Why the result is green? I expected the result color will be blue</p>