Visually separate sidebar from map

### Before
![before](https://f.cloud.github.com/assets/1269165/955556/7a4ca24a-042c-11e3-8595-4ae3f7c33c8c.png)

### After
![after](https://f.cloud.github.com/assets/1269165/955558/82c91fa2-042c-11e3-8f1d-7cc46336e21f.png)

Just something that visually bothered me :smile: