API Sidebar Links Are Too Bold

After the last push the API links got super bold. This appears to fix that.

__Before:__
![screen shot 2014-05-21 at 10 29 12 am](https://cloud.githubusercontent.com/assets/183799/3044231/d37c1984-e10f-11e3-8a26-ab50f18641f4.png)

__After:__
![screen shot 2014-05-21 at 10 28 57 am](https://cloud.githubusercontent.com/assets/183799/3044240/e38d8038-e10f-11e3-9c92-183444ce3c07.png)