An user script of general application is one which changes the background colour of some sites. Also, for facebook only, FBPurity. https://greasyfork.org/en/scripts/979-nobrighter https://www.fbpurity.com/

I use bookmarklets also to change background colour. Two are based on a script posted on reddit, two others from https://www.squarefree.com/bookmarklets/.

I'm not seeing any such posts on fedia.

It no longer shows on about:about (look at that to see what else is available) so, yes, it seems to be no more.

You will have to create if yourself with autoconfig. https://www.userchrome.org/what-is-userchrome-js.html

There are some details here :

https://searchfox.org/mozilla-release/source/browser/base/content/browser-sets.inc

I have never tried to do that. I understand there are details at the link below.

https://searchfox.org/mozilla-release/source/browser/base/content/browser-sets.inc

I see no icon on fedia. Is it supposed to be in the same place as the icon in lemmy (top left)?

How have you "configure[d] Firefox to load these pages"? You can simply leave those pages open when you exit Firefox, as long as you do not 'exit' by closing windows. Then set your home page and new tab page to "blank pages".

Where do you see that strict ETP sets your time zone to UTC? Setting resistFingerprinting to true does that.

Look at this post by MrOtherGuy : https://lemmy.world/post/687686. For a menu item added by an extension, you should use its label, e.g. menuitem[label="Copy Tab Title and URL"]. Are you aware that there is a FirefoxCSS on this site? https://fedia.io/m/FirefoxCSS/

It is still there on my Linux OS but hasn't worked for some years. I have had to use KDE to hide the title bar; perhaps you can do something similar. Check about:policies in case your distro is disabling the option.

I'm still getting the hang of this site. I thought I replied to your comment but my reply showed separately. I get the same result as the OP.

I also use auto tab discard. This is the only tab to which it prepends a z.