Make it work better with pelican-ipynb

[spapas]

I recently tried to integrate pelican-ipynb (https://github.com/danielfrg/pelican-ipynb) with this theme. Unfortunately, the styling that ipynb applies when using an ipynb file directly as a content type is not very good (everything is pushed to the right, there's a prompt displayed on markup cells etc).

I did some changes so the styling to make it tolerable (check https://github.com/spapas/pelican-octopress-theme/blob/master/static/css/extra_style.css) however that leaves much to be desired.

It would be great if somebody fixed the styling of this theme so that ipynb files would be displayed nice.