Align share buttons

Chrome
![image](https://f.cloud.github.com/assets/810040/2116806/cb1bc854-909f-11e3-86d1-901c798d567d.png)

Firefox
![image](https://f.cloud.github.com/assets/810040/2116809/d2102c4a-909f-11e3-8a6a-977e842c1b51.png)