UI polish

Minor UI fixes. Highlights:

More obvious active states using borders (Documentation and OAuth):

![screen shot 2013-11-21 at 16 56 59](https://f.cloud.github.com/assets/211284/1593046/ea84e788-52c5-11e3-80d5-a7f42c2f1cc2.png)

Better click areas. Before vs after:

![screen shot 2013-11-21 at 16 57 48](https://f.cloud.github.com/assets/211284/1593060/ffd72d44-52c5-11e3-8977-5857bf9c209a.png)
![screen shot 2013-11-21 at 16 57 36](https://f.cloud.github.com/assets/211284/1593061/01e28282-52c6-11e3-80fd-88c3b804eae8.png)

Fixed margin bug on some pre elements (very rare):

![screen shot 2013-11-21 at 17 07 51](https://f.cloud.github.com/assets/211284/1593158/456f428c-52c7-11e3-8212-699cbe00afc5.png)

After:

![screen shot 2013-11-21 at 17 09 04](https://f.cloud.github.com/assets/211284/1593161/4b6dbf1a-52c7-11e3-9ea4-9aa486270db5.png)