One of the most surprising Gwern.net bug reports was from a compulsive highlighter who noted that the skip-ink implementation (which uses the old text-shadow trick, because frustratingly, the recently standardized skip-ink CSS still manages to fail at its only job and it looks awful) looked bad because of how browsers handle shadows and highlighting.

We had known about that (and it can't be fixed because browsers don't let you control the highlighting), but we had never imagined it'd be a problem because you'd only see it briefly when once in a while copy-pasting some text for a quote - right? I mean, why else would anyone be highlighting text? You'd only highlight small bits of text you had already read, so if it looked bad in places, that was fine, surely.

(Narrator: "It was not fine.")

Just another instance of Hyrum's law, I guess...

We decided to WONTFIX that because we can't easily fix that without making it uglier for users who don't abuse highlighting and are reading normally, which is almost everyone else.