Note that these properties may return different values per operating system
The last three versions of Mac OS X use three different system UI fonts: Lucida Grande on Mac OS 10.9 (Mavericks); a special version of Neue Helvetica on Mac OS 10.10 (Yosemite); and a special version of San Francisco on Mac OS 10.11 (El Capitan).
-apple-system
andBlinkMacSystemFont
via http://furbo.org/2015/07/09/i-left-my-system-fonts-in-san-francisco/ Also related to #28Note that these properties may return different values per operating system
via https://www.smashingmagazine.com/2015/11/using-system-ui-fonts-practical-guide/#details-of-approach-a
Also a great source at https://bitsofco.de/the-new-system-font-stack/