title: DOMException: Failed to execute styleSheet.insertRule
body: <p>I am attempting to insert a rule into a stylesheet. The rule is valid (I think) and is taken from normalize.css (<a href="https://github.com/necolas/normalize.css/blob/master/normalize.css#L206-L212" rel="nofollow noreferrer">https://github.com/necolas/normalize.css/blob/master/normalize.css#L206-L212</a>) my code is:</p>
  
  <pre><code>var styleEl = document.createElement('style');
  document.head.appendChild(styleEl);
  var styleSheet = styleEl.sheet;
  styleSheet.insertRule('button::-moz-focus-inner, [type="button"]::-moz-focus-inner, [type="reset"]::-moz-focus-inner, [type="submit"]::-moz-focus-inner{border-style:  none;padding:  0;}');
  </code></pre>
  
  <p>Chrome (75.0.3770.100) throws the error:</p>
  
  <pre><code>VM381:1 Uncaught DOMException: Failed to execute 'insertRule' on 'CSSStyleSheet': Failed to parse the rule 'button::-moz-focus-inner, [type="button"]::-moz-focus-inner, [type="reset"]::-moz-focus-inner, [type="submit"]::-moz-focus-inner{border-style:  none;padding:  0;}'.
      at &lt;anonymous&gt;:1:12
  </code></pre>
  
  <p>The code above is used to insert other rules and works fine. It's just this rule that fails. Is this a malformed rule in normalize.css?</p>