Updated nav styles for new taglines. Hides taglines on tablet.

Desktop:
![screen shot 2014-03-13 at 3 11 45 pm](https://f.cloud.github.com/assets/583202/2413897/619f4fa0-aae3-11e3-9a08-3cf3ec784fe9.png)

Phablet:
![screen shot 2014-03-13 at 3 11 51 pm](https://f.cloud.github.com/assets/583202/2413898/68de872c-aae3-11e3-914a-4b44feb323e5.png)