tc39
The toolbox and grammars don't mesh well
While reading, I can sometimes follow along with the mouse cursor just under the line I'm trying to read. It happens mechanically, unconsciously, especially when I'm tired.
If you do that while reading grammars, you end up with the toolbox covering what you are trying to read, which is suboptimal.
It may even be an a11y concern for dyslexic folks. Likewise, the grey box on hover seems more distracting than useful.
https://github.com/tc39/ecmarkup/pull/154 lets one dismiss it with "esc", but it is a one shot solution, and it is not discoverable (unless one happens to be scouring the GH issues about the tooltip).
It would be IMO better to have a small, dedicated hover box on the left side of each rule. You could highlight it slightly when the corresponding line is hovered, thus giving a visual cue that it is interactive.
