Removed wrapping button tag

I assume the wrapping button tag is wrong here!?

```css
<button class="button button-icon">
  <div class="bar bar-header">
    <button class="button button-icon icon ion-navicon"></button>
    <div class="h1 title">Header Buttons</div>
    <button class="button button-clear button-positive">Edit</button>
  </div>
</button>
```