fixing gallery lightbox infobutton style

before
--------
![image](https://cloud.githubusercontent.com/assets/960919/4302928/c1e4f788-3e5f-11e4-8c67-19a9b975d0e2.png)
after
------
![image](https://cloud.githubusercontent.com/assets/960919/4302924/ac91f48a-3e5f-11e4-8358-2445f0381d21.png)

does this need both the viewbox and dimensions?