I'm so happy to see directives like these making it into css! It's great to have super granular control of every dimension and stuff, but in terms of creating layouts etc it really needs higher abstraction properties like this. I think this is why css was always so frustrating for me: caring about the technical side of things instead of the actual design implementation, which I now realize is not entirely my fault, but rather by design of the sepcs. (I still need to learn about layout fundamentals etc, but this certainly helps getting a grasp of things)