Fixed #5: .selector container clears float

Used the solution from http://www.quirksmode.org/css/clearing.html to fix selectors.

Without patch:
![without](https://f.cloud.github.com/assets/94636/1191004/8bcf86e4-2444-11e3-955f-ddf597bc0a83.png)

With patch:
![with](https://f.cloud.github.com/assets/94636/1191003/8bb4a91e-2444-11e3-9323-f424f4e8d2e8.png)