Eliminated the margins for InvisibleMixin

Before:

![image](https://cloud.githubusercontent.com/assets/21784/5293097/da7dcda0-7b28-11e4-8423-220bb35b0e8b.png)

After:

![image](https://cloud.githubusercontent.com/assets/21784/5293104/e697b2fe-7b28-11e4-8233-dad2b82b7b2f.png)

'Nuff said.