Update to footer styling

![screen shot 2014-08-22 at 11 29 47](https://cloud.githubusercontent.com/assets/867233/4009648/598c92b8-29e7-11e4-9b8a-ec775c3d4b45.png)

into 

![screen shot 2014-08-22 at 11 30 18](https://cloud.githubusercontent.com/assets/867233/4009650/5ea8a746-29e7-11e4-85a5-c3858f9e0da7.png)

`$gap` would probably be a better name for the `$gutter` parameter