Feature Proposal: Add :focus-within @variant

[paulozoom]

I'd be useful to have a :focus-within variant, for better styling control in forms.

Functionality-wise, it'd work exactly the same has focus, active, and hover, as its rules would too follow the structure .[variant-name]:[class-name]:[variant-name], with no side-effects.

[paulozoom]

If I'm not mistaken, this’d only imply changes in these two:

https://github.com/tailwindcss/tailwindcss/blob/0f0a4f45e8e2122e99850d11ad2c576be249e366/src/lib/substituteVariantsAtRules.js#L21-L34

https://github.com/tailwindcss/tailwindcss/blob/0f0a4f45e8e2122e99850d11ad2c576be249e366/src/lib/substituteVariantsAtRules.js#L51-L55

…plus the corresponding tests, correct?

If so, I can surely contribute those changes, if there’s a go-ahead from the core team on the feature.