The even/odd page margins must have the same value

The even/odd page margins have different values which makes pdf layout weird. 

You can see the issue looking at this screenshot:
![screen shot 2013-08-23 at 3 21 01 pm](https://f.cloud.github.com/assets/133986/1018945/c4d59c48-0c35-11e3-9795-60cd5af2ef07.png)