Style notebook as a document

Try for @ellisonbg #7243

![capture d ecran 2014-12-16 a 11 34 47](https://cloud.githubusercontent.com/assets/335567/5452119/9cf4bde2-8517-11e4-99b0-c96af5ef86cc.png)

Could you also disable these for the print media?  That will make it so `meta-p` print doesn't print with the gray background.