Top bar, fixed and contain-to-grid

Hi guys.

I'm using a top-bar, fixed and contained to grid. I also set my topbar to not to scroll to top on click. My markup:

```
<div class="contain-to-grid fixed">
    <nav class="top-bar" data-options="scrolltop:false">
        <!-- commented for brevity -->
    </nav>
</div>
```

This is happening on phones or browsers resized like a small screen. 
I don't really know if this is an expected behaviour, my markup is wrong or it's a bug.

If I disable the scrolltop (`scrolltop:false`), when I click to toggle the topbar disappears (actually, if I scroll up a little bit it's there).

If I enable the scrolltop (`scrolltop:true`), it works perfectly, but I'm forcing the user to scroll top every time he opens the menu. This is also the case if I don't set any *data-options* as `scrolltop:true` is the default.

I've uploaded a demo: http://fedeisas.com.ar/test/. Resize your browser like at <~768, scroll content and click to toggle the menu.

I've tried a sticky approach but it flickers a lot when scrolling.

Is there any way to have a fixed contained to grid topbar that remains fixed all the time?

Thanks!