Sorry for the inconvenience. Known Navigation header breakage.
There may be other unforeseen breakage primarily in the handbook portion of the wiki.
The Table Of Contents section of each "PC-BSD® Users Handbook" page may be the best workaround.
All versions of the PC-BSD Handbook are released under the Creative Commons Attribution License. This means that you are free to distribute, modify, translate, and convert the Handbook to other formats, as long as your version retains the following attribution text:
Copyright 2010-2011, The PC-BSD Project.
PC-BSD and the PC-BSD logo are registered trademarks of iXsystems.