title: Unable to focus on a checkbox with tabindex
body: <p>I am unable to focus on a checkbox with tabindex=0. I think this is due to display and opacity setting  </p>
  
  <pre><code>.newCheckbox input[type=checkbox] {
     display: none;
      opacity: 0;
  }
  </code></pre>
  
  <p>I also have a label before the checkbox. Is it possible to change the code to make the checkbox label appear highlighed - to give an appearance as if the checkbox is highlighted on tab.</p>
  
  <p>plunkr -     <a href="https://plnkr.co/edit/6ecZu1G8tKzztGGbK4G3?p=preview" rel="nofollow noreferrer">https://plnkr.co/edit/6ecZu1G8tKzztGGbK4G3?p=preview</a></p>