(In reply to MarjaE from comment #14)
Firefox for Mac, 95.0.2 when I reported this, and whichever Nightly when I checked the default behavior in Mozregression.
So wait, what is your
browser.display.use_system_colors set to? That's the checkbox in the color settings in about:preferences that says "Use system colors" (in English, that is). I tried to reproduce the gray color you mentioned with the "Always" setting, but for me, it's still #ffffff on 95. Pretty sure that gray color is not defined in fx source code so maybe it differs by macOS version.
Anyway, I think you might be misunderstanding me. I said that userChrome.css is not going to break someone's Firefox installation or profile. I didn't say that users don't need userChrome.css, or that not having it would cause accessibility issues. Just the opposite really. If you had read my comments, you would know that I use it myself. I have over 10,000 lines of CSS in my profile and publish an enormous userChrome.css theme for public consumption. I am an extensive user of the system, you don't need to convince me that it's worthwhile.
I wasn't addressing you in my previous comments at all. Rather, my comments were directed to Sören, who argued that stylesheets should not be synced because if they get downloaded when we log in on another computer, and that computer has an older or newer version (or different release channel) of Firefox installed, it could break something. My point is that it might make something look ugly, it might not appear as intended without further user modifications, but 1) that's not breaking Firefox, and 2) that has nothing to do with syncing the stylesheet. The same thing would happen if we manually installed the stylesheet.