adjust padding for mobile screens so menu is viewable

Fix for unreadable menu on mobile phones.

Left side image is the production version of menu viewed in a mobile view. Right side is with adjusted CSS for screens smaller than 768 pixels. 
![screen shot 2014-09-07 at 11 19 58 am](https://cloud.githubusercontent.com/assets/1028443/4178724/d5e944a0-36a3-11e4-984d-bfc4187bcd83.png)