2 small bugs.

This fixes 2 things. I wanted to make two separate pull requests but apparently I should have used two separate branches (?) to do that? Sorry, I am still a GitHub newbie.

This contains #6 where it fixes the CSS for `pre` which uses 2 different properties since 1ff71b7ba1, and also switches `fixed-width` to `monospace` in the `font-family`. That’s the only right generic font family according to [the spec](http://www.w3.org/TR/CSS2/fonts.html#monospace-def) (also [CSS3 spec](http://dev.w3.org/csswg/css3-fonts/#monospace-def)).