>> Unfortunately Classilla is no longer updated.

> Did Cameron Kaiser stop development of Classilla?

From 2½ months ago:

"just a note to Classilla users. I do have some work done on a 9.3.4 which fixes some JavaScript bugs, has additional stelae for some other site-specific workarounds and (controversially, because this will impact performance) automatically fixes screen update problems with many sites using CSS overflow. (They still don't layout properly, but they will at least scroll mostly correctly.) I will try to push that out as a means of keeping the fossil fed."
http://tenfourfox.blogspot.com/2016/09/ars-technicas-notes-from-os-9.html