WAM: visual tweak style of pages

First cut of a new visual style for the web assessment methodology pages.  Feel free to tweak as needed @cfarquharson.  

Related to #4314.

![wam-style](https://f.cloud.github.com/assets/2110107/1933616/76eba0ec-7ede-11e3-8ba6-554dd94b9e49.png)