What is this class, focus-visible:ring-ring what does it do?

[srinivasreddy]

What is this class focus-visible:ring-ring what does it do? I see it button.tsx, I understand the ring functionality. But I couldn't find any reference of it online? Was that a typo?

[flixlix]

This is whatring-ring does. It basically just sets the color of the ring to be used as the --ring custom css property defined in your css.

In these cases, extensions are your friend for checking the css behind a tailwind class.
https://tailwindcss.com/docs/editor-setup#intelli-sense-for-vs-code