Sierra will be great for Framer, because we get a free ride on all the new stuff in WebKit. Here is an official overview of everything new in WebKit.
I'm most excited about: inline videos on mobile, configurable image rendering and a faster js profiler.
"Support for #RGBA and #RRGGBBAA" finally! Now I can stop trying to convert Hex to rgb() when I want to use alpha
If you want a great technical overview of all of Sierra, read the Ars review: http://arstechnica.com/apple/2016/09/macos-10-12-sierra-the-ars-technica-review/
But does it support 'navigator.mediaDevices.getUserMedia'....