Sorry for the inconvenience. Known Navigation header breakage, its being "rebuilt."
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.
I am not a English native speaker (writer). My language skills are horrible and I am truly sorry about that. So please check my contributions!
Anders ist das bei deutsch! :-D
Please feel free to change my words (also in discussions and anything else) in a better (more comprehensible) English. I would be thankful for that.