I like the concept and the C# code is just hands down the best example out of all of them (yet another reason I miss coding in C#).

I'm curious though, will this be eventually ported to JavaScript? Yeah yeah I know "flexbox is already on the web!" but if you could write a layout in this fashion versus using style sheets then you could take it and directly apply it to any of your applications (even if you have to convert between languages the exact same setup is still there it's just a straight up conversion).

Overall cool idea and implementation. Curious to see where it goes from here.