Really nice article on the :focus-within pseudo-class! Really good use of it! 🥳
I would just like to make a few clarifications, if you don't mind.
::before and ::after are pseudo-elements and not pseudo-selectors. And technically :focus-within is referred to as a pseudo-class.
Pseudo-elements should generally be used with double :: to tell them apart from pseudo-classes which should be referred to with a single :. They are all used together in CSS selectors.