Responsive nav fixes

- [fix] break on two lines when there is a signposting at wide breakpoint
- [fix] don't show a border on the right of the nav if there is no local navigation at wide breakpoint
- [new] Use heading 1 type
- [new] section title width adapt to the left column on large devices

After that and @tudorraul's fixes, we're ready for release.

![screen shot 2014-07-10 at 11 31 39](https://cloud.githubusercontent.com/assets/85783/3537300/7f14e986-081d-11e4-9f3b-8394beeb32df.PNG)


![ ](http://lastangryfan.com/wp-content/uploads/James-Blake.gif)