I never really "got" the float model for layout, so Grid is a welcome improvement these past few years. That said, this is still missing the one thing I've yet to find in any discussion of CSS.

How to appropriately size text. No -- for the 1,000,000th time -- I will not use Modularscale, which feels obtuse to me. Using some formula on a website that someone says works also feels arbitrary. Not to mention that the SASS implementation hasn't been touched in years.

With Grid, I felt like it was the first time I saw someone create a layout where it was obvious what was going on. I have yet to see something like this system - but for text sizing.