>As someone who has spent years implementing those standards, a reference implementation would not help me at all.

I don't quite understand what you meant your comment to be indicative of. That nobody else would consider it useful? That you personally see no value in reference implementations at all?

>Dear imgui's layout model doesn't scale at all, due to the fact that it's immediate mode. It redoes layout from scratch every frame.

Could you detail the UI are you thinking of where IMGUI is inefficient but HTML/CSS isn't? Not asking for a formal spec, just a general usecase..

My problem with CSS/HTML is that productivity scales inversely when using them.