I’ve found that the easiest way to live debug userChrome.css is to:
- Open the browser toolbox,
- Go to the style editor tab,
- Write userChrome in the search box to find it,
- Write CSS directly into the browser toolbox integrated editor.
The integrated editor reloads CSS changes as you write, even without saving.


Thanks, going to try this at work. So far I had used tab group names for short comments, but it’s not great in those cases where I have a group of tabs for one topic and want to remember that one tab has open todos and another is waiting for a blocker etc.