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.
Set Root Password Screen/10.0
This configuration screen, seen in Figure 4.4a, requires you to set the root password. The password must be a minimum of 4 characters, and you are required to type it in twice to confirm the password. Click the "Next" button when you are finished.