Yeah... It's a bit hard to balance things like this though, I've seen lot's of folks complain about how their Firefox is apparently "broken" because it now suddenly has this empty margin around web-content seemingly wasting space for no reason - and then it turns out that they have deliberately turned this very feature on. And that is even if the feature is completely hidden - I wonder how many more complaints there would be if options like this are made more accessible.

The letterboxing feature has been in Firefox since 2019 - starting from Firefox 67 I think. The preference for it might have been hidden though so maybe it's just relatively unknown feature - I don't know if or how visible LibreWolf makes makes it for the user. But regardless, any modern Firefox variant probably has that capability.

Sounds like you are talking about Firefox's letterboxing feature which you can enable/disable independently from full fingerprinting resistance.

I'm not sure if resistFingerprinting does anything to stop websites from uploading whatever data they can get though, I don't think it does that. And I don't think it could really do that in the first place since the website could just obfuscate the data and browser wouldn't know what is sent.

You'll be styling another element, that's really all it is.

Normally Firefox applies various styling rules to the element with id urlbar-background - so it makes sense to also apply your custom style rules and overrides to it. If you apply your background-color or border or other rules to some other element such as #urlbar-input-container then the original styling of #urlbar-background still applies as well.

This would then cause issue like you would see in your first image, exactly like you guessed; the outline of #urlbar-background is seen behind the background-color of #urlbar-input-container because the two boxes don't have exactly the same shape and thus you are not fully covering the urlbar-background.

If you aren't doing anything else to urlbar then I'd recommend styling #urlbar-background instead of #urlbar-input-container - like this:

#urlbar-background {
  border: none !important;
  border-radius: 5px !important;
  background: light-dark(#ffffffff, #1b1e20ff) !important;
  outline: none !important;
}

That's not necessarily a good solution either, because a service could figure out that the source of random fingerprint data likely comes from the same user. Especially if your ip is not changing. It might perhaps be effective if a substantial amount of people were doing it though.

But to generate such random fingerprint is difficult because it consists of many parts and services don't all build fingerprints the aame way. You could easily randomize e.g. canvas data, but the issue is that if you only randomize one data point then that one random data point pretty uniquely identifies you if your other datapoints are stable. So to be effective you would really need to randomize several different datapoints and that may not be such an easy task since websites could build them in all sorts of ways.

You can change it like this with userContent.css:

@-moz-document url("about:newtab"), url("about:home"){
  :root{
    --newtab-primary-action-background: #f00 !important;
  }
}

That way you can specify a color for them, but setting the value to AccentColor may or may not resolve to the actual system accent color.

It's all good my dude. There's just so many small differences between just linux versions that I wouldn't have been suprised if the style didn't work in one of them.

Is your style up-to-date? This sort of sounds like issue #359 but that should have been fixed 2 months ago.

Well the feature development is certainly progressing - here is the tracking bug for it.

You can nowadays just test it in normal nightly without special build - it's extremely incomplete, but you can test it if you wish. It's tied to revorked sidebar which you need to enable in about:config.

I'm not sure about how the svg would work here (though it might work fine), but you can do that with just CSS as well:

@keyframes tab-gradient-anim{
  from{ background-position-x: 0% }
  to{ background-position-x: 200% }
}
.tab-content[selected]{
  background-image: linear-gradient(
        90deg,
        rgb(255, 0, 0) 0%,
        rgb(255, 154, 0) 12%,
        rgb(208, 222, 33) 24%,
        rgb(79, 220, 74) 35%,
        rgb(63, 218, 216) 44%,
        rgb(47, 201, 226) 50%,
        rgb(28, 127, 238) 60%,
        rgb(95, 21, 242) 70%,
        rgb(186, 12, 248) 80%,
        rgb(251, 7, 217) 90%,
        rgb(255, 0, 0) 100%
    );
  background-repeat: repeat-x;
  background-size: 200% 100%;
  animation: tab-gradient-anim 2s infinite linear;
  background-clip: text;
  color: transparent;
}

Absolutely not. If anything, public officials would be the one group whose messaging I would understand being scanned so that the people can sort of keep them on check. But again, implementing such possibility that would still weaken security of everyone else as well so of course it should not actually be done.

Yeah, sorry I missed the question about the popup. Yes, you can change it, but it's via userContent.css not userChrome. Could look like this:

@-moz-document url("chrome://devtools/content/styleeditor/index.xhtml"){
  .menupopup-arrowscrollbox{
    background: #f00 !important;
  }
}

Note that this only changes the popup that appears in style editor because the other parts of the toolbox are separate documents. Also, it only works for "normal" devtools but not for browser toolbox - to affect that you need to first set up userChrome.css for the toolbox profile, it's literally a separate firefox profile stored inside its target profile in a chrome_debugger_profile directory.

I think I looked into this some time in the past and it turned out that to do this, you need to use autoconfig scripting to inject a stylesheet as an agent style. Then, you can use style like this:

@namespace url('http://www.w3.org/2000/svg');

#box-model-elements{
  --highlighter-box-content-color: hsl(297, 71%, 53%);
}

I'm limiting that style to only apply to svg elements by namespace, because otherwise the style will apply to all websites as well. But nonetheless, this would also set this custom property to all svg elements in any svg that has has that particular id. Not a huge deal, the point is simply that you need to do something to limit the scope the you want to apply changes to.

Yup, YT has only shown me a nice "Sign in to confirm you’re not a bot" message for the past week or so. Not because of Firefox or adblockers though, because the same happens on all other browsers and clients as well.

Maybe because of VPN, or who knows what, maybe they are just idiots.

Indeed. I mean, I'm blocking ads as much the next guy and that's not going to change in any foreseeable future, but I cannot see how introduction of privacy preserving advertising platform could possibly be seen as anything other than an improvement over the current, completely perverse, situation. It would be better for people who don't block ads, so if this acquisition would advance uses of privacy-respecting advertising systems and simultaneously get some revenue to Mozilla then this sounds quite like a win-win to me.

Yeah, seems bunch of ids inside urlbar-input-container got replaced with classes in bug 1610530 - this was one affected style. Although this one was a bit broken even before that change I think.

I don't. Pretty much everything just goes to other bookmarks. When I want to use them I'll just type * to urlbar , type something about it and Firefox usually finds the bookmark I wanted.

I mean simply like this:

:root{ 
  backdrop-filter: brightness(99%);
}

Alternatively html selector would also work to refer to the document root element - about:newtab is a html document after all.