Netscape changed massively between 4 and 6 (which was the first version based on the Mozilla codebase). AFAIR in 4 CSS support was very preliminary, while in 6

Netscape changed massively between 4 and 6 (which was the first version based on the Mozilla codebase). AFAIR in 4 CSS support was very preliminary, while in 6 it was best what you could get at the time.