Fixed CSS font stacks for Helvetica Neue (see #1).

This fixes the font stacks used for Helvetica Neue Condensed Bold and Helvetica Neue Light, causing Firefox to use the right font. Doesn't fix the wrapping issue yet, but at least the proper font weights are used now in Gecko as well as WebKit.

![font-fix](https://f.cloud.github.com/assets/405124/487913/dc2e1c00-b96d-11e2-80b7-1daf00009e28.png)