title: invalid pseudo-element or pseudo-class
body: <p>My css page validated with no errors around a month ago, and I have not edited the lines of code I am getting errors for.</p>
  
  <pre><code>form input:required:focus{
      border: 3px solid red;
  }
  
  form input:invalid{
      border: 3px solid grey;
  }
  </code></pre>
  
  <p>The errors I get are:
  "Unknown pseudo-element or pseudo-class :required" and "Unknown pseudo-element or pseudo-class :invalid".  I am validating for CSS Level 3.</p>