When viewing source code on GitHub, their CSS specifies the following fonts:
font-family: SFMono-Regular,Consolas,Liberation Mono,Menlo,Courier,monospace;
Even though I have SFMono-Regular installed on my Mac (in ~/Library/Fonts/SFMono-Regular.otf), Firefox uses Menlo to render the element. Both Safari and Chrome correctly use SFMono.
How can I get Firefox to detect and use the fonts installed in ~/Library/Fonts?
From Mozilla Support
This can happen when Firefox has a problem to access locally installed fonts because of sandbox security issues.
https://wiki.mozilla.org/Security/Sandbox
You can set this pref to 2 or 1 on the about:config page to lower the sandbox security setting.
security.sandbox.content.level = 1
close and restart Firefox to make the change effective.
If '1' still doesn't have effect then try '0' to disable the sandbox.
If this didn't work then undo/reverse the change and reset the pref via the right-click context menu to the default value.
You can open the about:config page via the location/address bar. You can accept the warning and click "I accept the risk!" to continue.
http://kb.mozillazine.org/about:config
If you also have this problem on the about:config page then try to boot the computer in Safe Mode.
