The 'Full Screen' feature on cuts off on Firefox

[ThomasThelen]

When using the full screen feature on the browse page, the bottom cuts off. Note that this works fine in Chrome, and is relevant only to Firefox.

Steps to Reproduce

1. Launch Whole Tale in Firefox
2. Navigate to the Browse page
3. Full screen the page (see gif below)

[bodom0015]

I'm willing to bet that the black area at the bottom has dimensions that are precisely equal to the dimensions of the navbar + the footer. Firefox always has issues with using height: fill-available, so I wouldn't be surprised if that is manifesting here in the opposite way.

If you'll recall, Firefox typically has issues where divs are not properly stretched to match the height of the parent in some cases (usually with Semantic's class="ui grid"- see #202 #410 #468 #403 #402). I'm willing to bet that this is another one of those cases, where the height of the "full screen" app isn't being properly stretched to match the viewport.