flow-layout like semantics

You mean Grid layout, as it supports the fr unit which is currently defined there. Fun fact: it's also not part of Flex layout, even when the unit's functionality suggests it's related to flexible lengths.

And a side note: I am currently working on generalizing the definition for it and moving it to CSS Values 5.

The stripes() function only works in context. Currently it is defined for border-color and outline-color. Though that's still in flux.

So I'd suggest to wait until it's clarified where it'll end up and then add two new features for the individual uses.

Sebastian

I see your point @SebastianZ but I'd think the good side of CanIUse is that you can know about it even before it is ready, and join the discussion if you like. I normally don't read through the W3C drafts, and this site is a good summary of what's cooking.