What is really needed for supporting older browsers with V4?

[babycommando]

As many have noted across a wide range of issues and discussions, tailwind is currently not working for older browsers since these have no support for some "newer" features. It's sad because its holding back v4 implementation for a lot of great products, making them stuck in v3 (wich still works on older browsers) - with no access to the newest engine and features...

I don't know wich of these features are breaking, but if we could map out these maybe we can add some fallbacks so we don't just exclude a portion of users from our apps.