Workaround for Chrome Painting Bug with Background-Attachment:Fixed

Hey! Should I write in Portuguese or English ? haha.

Well, firstly, congratulations for the website and the event.

Secondly. I saw a little bug with the building in the homepage. Apparently, it's only occurring in Google Chrome.

![image](https://cloud.githubusercontent.com/assets/5850824/4587331/f914ee62-5029-11e4-9495-860c092ce630.png)

So, here is the solution, just a ``-webkit-transform: translateY(0);``. At the first moment I tried to force a repaint via javascript as you can see in the main.js file, but it's an ugly solution.
Desculpa por isso :/