Add footer style, improve flat list spacing on mobile, fix tagline underlines, small code clean up

I have some minor improvements! Here's the changes:

* Footer banner closes the page with style:

    ![](http://i.imgur.com/g2HkwQm.png)
* Improve flat list spacing on mobile view. This still works with multiple lines of buttons, so don't worry. :-)

    Before:

    ![](http://i.imgur.com/PuqhZiv.png)

    After:

    ![](http://i.imgur.com/KS7S1sD.png)
* Fix tagline underlines on-hover. They will now work as initially intended.
* Small code cleanup to keep both light and dark consistent.