Textual is quite nice (unsurprisingly): textual.textualize.io/

and its companion library rich is not bad either - maybe not quite as beautiful, but very clean and readable and useful: rich.readthedocs.io/en/latest/…

Honestly, I don't think I've come across any library whose documentation "maxes out" on beautiful IMO, but those two are among the best I can think of at the moment.

#Python

Arcade; I loved the tutorial: api.arcade.academy/en/latest/

Introduces concepts only when needed instead of overwhelming you with layers upon layers from day one.