Accessing the test class listings from Game Rules > Classes > Necroancer/Runesmith brings up well formatted versions with the proper fonts for headers, etc. but accessing them from Books > Impossible Class Playtest > Necromancer brings up a page that lacks the “pathfinder feel” styling for headers, etc.
This is odd. I tested on my end and there was a brief flash of the unstyled page that disappeared and was replaced by the properly styled version. It’s possible that your browser may be preventing the styling from loading correctly. I think I have your browser information in another thread so I’ll pass this along so we can see if this is something we can fix on our end.