[csswg-drafts] [css-pseudo-4] Add a highlight pseudo-element for find-in-page or scroll-to-text (#5233)

chrishtr has just created a new issue for https://github.com/w3c/csswg-drafts:

== [css-pseudo-4] Add a highlight pseudo-element for find-in-page or scroll-to-text ==
Right now you can customize the color of a selection highlight via [::selection](https://drafts.csswg.org/css-pseudo-4/#highlight-pseudo-element), but there appears to
be nothing for user agent-specified selections such as find-in-page and scroll-to-text-fragment.

How about we add `::ua-selection` ?

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/5233 using your GitHub account