Basically title...I'm wondering specifically if my chrome/userChrome.css is increasing my chances of getting fingerprinted/tracked/etc. I can't find answers on DDG or on Arkenfox's GitHub, so I'm probably good, but what do you think?
Probably not;
userChrome.cssjust modifies the local user interface of Firefox, right? I don't think any of this information is ever transmitted to servers, nor is it available from Javascript. Custom user styles however could probably be used for fingerprinting.Related interesting article from Mozilla: Privacy and the :visited selector
It will have no practically significant effect. Websites do not have access to browser chrome css properties. The worst it might do is change the dimensions of the viewport in a way that makes your browser fingerprint slightly more unusual, i.e. the same thing that would happen if you set the UI to "compact" mode.
CORRECTION: It was pointed out to me that I was confusing userStyles.css with userChrome.css. I'm not aware of anyway that styling the UI outside of the DOM could be directly detectable. Theoretically, if you could resize some UI elements that would change the viewport size and therefore be detectable. I'm not informed enough on userChrome.css to make that call however. Original comment is below.
Yes. As CSS styles can be queried, any differences can be used as an identifiable data point used to form a fingerprint.
Think what you're talking to more applies to add-ons like dark reader. Websites can't see what your browser visually looks like.
Maybe they can see if your userchrome js modified the height by seeing the viewport size, but that's getting way paranoid for it to be realistically used against you
Yes you are correct. Another commenter pointed out I was getting mixed up between user styles and user chrome. Funny that we both considered how modifying user chrome could potentially impact viewport size! We both have paranoid minds :P
