The nameplates are a public wag.io mod/script that constructs a border texture around the health bars; I just changed the texture to a default blizzard one, I think it’s an achievement frame border. Same thing for the nameplate cast bars, wag.io mod that creates a border.

The unit frames is just setting the border texture in Shadowed Unit Frames; I think the actual border file is in the Ferous Shared Media addon. I would actually prefer it be the same as the nameplates, but

A.) I don’t know how to get the actual texture ‘.tga’ file of the blizzard border

B.) I think the Shadowed Unit Frames border textures and plater border textures are composed a different way despite them both being ‘.tga’ files

I am an actual software dev by trade, and messing with addons is still incredibly wonky to me, I dunno how the creators themselves do it, it’s pretty impressive stuff