Apple has changed the default system font to San Francisco for most languages on the Mac since El Capitan, which was released over 2 years ago. Along side San Francisco, Ping Fong has also been the default font for Chinese to conplement San Francisco. I just installed Firefox Quantum, and looked at Facebook's UTF-8 feed, the Chinese characters are still rendered in SinoType Heiti. Worse, the Hong Kong Supplementary Character Set characters are rendered Ping Fong light, so obviously Firefox is at least aware of the existence of Ping Fong. Chrome has fixed this about a year ago. I've search around Bugzilla and didn't find a single issue reporting this. Are the dev aware of this issue at all?