First of all, great idea — a headless notification library is exactly what I need.
But it's not really headless, is it? The notification cards are headless, alright. But what about the notification area, the margins between notifications? What about the animations, those are hardcoded.
I think a headless library should limit itself to the logic and leave the styling and animations to the user. As is, this is unusable for me, for example, since we have our own design system and I can't just take someone else's design.