LPS-50302

https://issues.liferay.com/browse/LPS-50302<br><br>Hey Nate, I ended up modifying the respond-to mixin and using the naming convention from your gist. I thought this way was more flexible since you could mix min and max sizes to target specific screen widths if you wanted.

![media-query-mixin](https://cloud.githubusercontent.com/assets/788266/4390585/42cef242-43fe-11e4-9304-80b169cc43d4.png)