Earlier quoted context omitted.
They seem to have intentionally done this, by setting ::selection to transparent. I don't understand why some people think this is a good ideal, for colorblind people this is a real nuisance.
For anyone who wants to select and copy text, this is a nuisance as well. (I wanted to quote something from the page in a comment here, for instance.)
What really annoys is that browsers still select page text as it lays in HTML, ignoring CSS that places it differently. Also the entire fact that selection spans really different blocks, so you have to aim precisely to start and end it at appropriate places.
The main purpose of browser is to manage hypertext. How could that be implemented wrong?