http://gothub.nowhevi57f4lxxd6db43miewcsgtovakbh6v5f52ci7csc2yjzy5rnid.onion/tonsky/FiraCode/wiki/IntelliJ-products-instructions
It has been reported here NOTE: There’s an issue on OS X when Fira Code Light is used instead of Regular weight by default ( discussion ). To work around that, do not install Light weight at all. (this is fixed in latest 16 EAP) Also, installing TTF as opposed to OTF renders better with IntelliJ on the Mac.