In Tor, I see a border around every webpage. I think it might be to hide fingerprints, but it really annoys me. Is there any way I can remove it?
I am using Tor 9.0.2 on Windows 10
This new feature is called, "Letterboxing"
Tor Browser, in its default mode, is starting with a content window rounded to a multiple of 200px x 100px to prevent fingerprinting the screen dimensions. The strategy here is to put all users in a couple of buckets to make it harder to single them out. That worked until users started to resize their windows (e.g. by maximizing them or going into fullscreen mode). Tor Browser 9 ships with a fingerprinting defense for those scenarios as well, which is called Letterboxing, a technique developed by Mozilla and presented earlier this year. It works by adding white margins to a browser window so that the window is as close as possible to the desired size while users are still in a couple of screen size buckets that prevent singling them out with the help of screen dimensions.
If you don't want to use it, that's fine. Just be aware that using Tor Browser in fullscreen mode can help fingerprint you as a user.
How do you disable it?
go to about:config
change the privacy.resistFingerprinting.letterboxing to false.
Removing it will put you in the probably less than 1% of people that have done so, making fingerprinting you 99% easier, and honestly, it'd probably make uniquely identifying your computer 99.99% easier because you'd be 1 in 10000 to have removed it and have a specific device with those specific dimensions in full screen.