Great tip. I just like to add some precision in terms. focus-within is a pseudo-class. There're pseudo-classes and pseudo-elements, the selector is the full "query" part of the CSS rule.
A CSS pseudo-class is a keyword added to a selector that specifies a special state of the selected element(s). For example, :hover can be used to change a button's color when the user's pointer hovers over it.
A CSS pseudo-element is a keyword added to a selector that lets you style a specific part of the selected element(s). For example, ::first-line can be used to change the font of the first line of a paragraph.
Great tip. I just like to add some precision in terms.
focus-withinis a pseudo-class. There're pseudo-classes and pseudo-elements, the selector is the full "query" part of the CSS rule.:hovercan be used to change a button's color when the user's pointer hovers over it.::first-linecan be used to change the font of the first line of a paragraph.MDN: Pseudo-classes and pseudo-elements
100% correct on the terminology here.
Thanks for the addition