Context
I know that styling is subjective, so feel free to ignore this suggestion, but I would still like to record it.

When I hover on the copy button, two different tooltips saying essentially the same thing are printed. I find this a bit weird and would prefer just one tooltip.
I did this on a project using custom CSS here:
https://gitlab.com/extending-lilypond/extending-lilypond.gitlab.io/-/blob/main/static/better-copybutton.css#L14
Proposal
Either remove one of the tooltips entirely, or make it optional.
Tasks and updates
No response