Add CSS media query to improve logo position

When using mobile devices the SWC logo overflow the box as showed below:

![screen shot 2014-03-02 at 13 35 17](https://f.cloud.github.com/assets/1506457/2438660/7a8a81b0-adf4-11e3-9ad7-5b51a3d3a5f4.png)

This PR add a small CSS media query to avoid this problem (as showed below) using the same query used in for others elements.

![screen shot 2014-03-02 at 13 44 03](https://f.cloud.github.com/assets/1506457/2438697/debeed60-adf4-11e3-9d62-f572525145c2.png)