My tip for everyone using Firefox on pc: install the tree style tabs plugin!
I wish customizing GUI was easier on firefox than with userChrome.css.
After installing TST one would want to remove sidepanel header and default horizontal tabs.
@bentropy @koorool while im used to using userChrome it would be good to have a gui tool for those not familiar with inspector tools and css. I don’t think the extension api grants the access needed for an extension to work
For what it’s worth there are a great number of ready made css snippets you can use
Those snippets could be a category on firefox AddOn store. With reviews, comments, screenshots etc, just like themes. Installable / previewable with a single click.
Who could deliver a feature request to Mozilla please? :)