I guess it'd be more accurate to call it a "Generator for CSS-Only Terrain", as the generator itself is not CSS-only.
It's a "(CSS-only Terrain) Generator", not a "CSS-only (Terrain Generator)"
https://xkcd.com/37/
It's a "(CSS-only Terrain) Generator", not a "CSS-only (Terrain Generator)"
https://xkcd.com/37/