Here’s a great thread by Ricky Mondello that outlines all of the nifty new features in the latest Safari across macOS and iOS. Some of my favorites include the ability to replace gifs with mp4s, the Payment Request API and support for the Web App Manifest.
Learn Chrome DevTools Deeply
Frontend Masters has an in-depth course all about Chrome DevTools. There is a lot to know, from editing, to debugging code and finding problems, to profiling web performance.