Comment by qingcharles

I guess wire up a codepen demo and try it out. I know the guys writing this were well aware of all the edge cases like that and these are some of the absolute smartest CSS people you can think of who had to write the very detailed spec for this.

I don't think the smooth reflow made it into the current spec, so I guess watch this space?

https://www.w3.org/TR/css-grid-3/