Even though my authoring style doesn’t match Harry’s one-to-one, there’s a lot of overlap and definitely some sound recommendations for front-end folks looking to write more maintainable CSS.
Web browser rendering performance recommendations
Lot’s of useful information here for anyone concerned about performance — which if you’re not, you should be. The tl;dr sections are great too if you’re pinched for time.
A new technique for setting responsive font sizes
It appears that by using calc() and vw we can get responsive typography that scales perfectly between specific pixel values within a specific viewport range. This means you can have perfect smooth scaling between any 2 font sizes over any viewport range. The font will start scaling and stop scaling exactly where you want.
(Via Chris Coyier)