It would be really great if CSS/JS properties and functionality could be flagged in the designer as either supported by a current baseline of modern browsers or not, maybe somehow connected to caniuse. It is a bit of a pain to happily work away in the designer on the presumption that everything you can do there will display correctly on an acceptable baseline only to find out later in testing that aspects need to be rebuilt.

Caniuse presents a baseline assessment at any give time for particular functionality and if webflow could connect to that knowledgebase and present a tiny green, amber or red circle on CSS functions the user could click to see a list of 'live' known issues related to the particular property etc.

Maybe an unrealistic wish? But that's what wishlists are for right? :)