fix nav-bar failing if browser's width less than 1200px

Very simple fix. Sometimes I work from my laptop with not very big screen resolution, not Retina yet :) and I see something like you can see on the screenshot.

![screen shot 2013-08-17 at 18 04 54](https://f.cloud.github.com/assets/169803/981372/2cd033d4-075f-11e3-97bc-9e9dbb169ea4.png)