I'm glad we can use logical properties now. Dealing with systems that support both LTR (like English) and RTL (like Hebrew and Arabic) languages used to be a pain because we had to have a build script that generated a second CSS bundle with everything flipped (eg converts margin-left to margin-right, border-left to border-right, etc. Logical properties make it a lot easier.
I love the gap property for flexbox... I use that one all the time. Easily solves the "I need padding between all these items, but no padding at the start or end" use case.