The form component:

https://oat.ink/components/#form

Looks a lot like a raw HTML+CSS framework I made in 2009:

https://alganet.github.io/ghiaweb/ (it has some small glitches, browser widgets changed a lot since 2009).

Particularly the use of the label, fieldset and legend elements as native accessible solutions instead of instrumenting divs. Even the styling and the example resembles it a bit!

https://oat.ink/components/#grid

This is where it falls from grace IMHO. Grid classes are fundamentally non-semantic. I know they're popular and useful, but there must be a better (semantic) way of doing this. I haven't found it yet, but there must be.