title: Remove focus on mat-button-toggle-group in Angular Material
body: <p>I have this code from Angular Material site and when I used this in Chrome I have focused on the button(like a blue border for each button selected).</p>
  
  <pre><code>&lt;mat-button-toggle-group name="fontStyle" aria-label="Font Style"&gt;
    &lt;mat-button-toggle value="bold"&gt;Bold&lt;/mat-button-toggle&gt;
    &lt;mat-button-toggle value="italic"&gt;Italic&lt;/mat-button-toggle&gt;
    &lt;mat-button-toggle value="underline"&gt;Underline&lt;/mat-button-toggle&gt;
  &lt;/mat-button-toggle-group&gt;
  </code></pre>
  
  <p>I tried to remove this with outline:none in Css, but it doesn't work.</p>