Chen css

https://trello.com/c/I4jd7bHb/51-add-scss-and-gem-neat

![screen shot 2014-11-24 at 9 08 10 am](https://cloud.githubusercontent.com/assets/3759510/5165985/6f630b5a-73b9-11e4-9b70-b211fcd73b65.png)

in application layout
```ruby
<div class="header-nav left"> (line 21)
<div class="header-nav right"> (line 29)
```