There weren't any straightforward guides when I looked this up, and I even had to ask myself. But I just needed to put so and so together, get some feedback here, and voila! Hopefully this can work for you too, and could edit userchrome.css in your favorite editor, and see the changes in Firefox immediately. I tested that it works with @import url("folder/file.css");, and nested imports too (if folder/file.css contained @import url("Another folder/file.css");.

1. Install fx-autoconfig (I haven't tested it with other Firefox JS loaders), following the whole install section: https://github.com/MrOtherGuy/fx-autoconfig?tab=readme-ov-file#install
2. In the chrome/JS/ folder, create <any file name>.uc.mjs (I named mine refresh.uc.mjs) and paste the script below (it's slightly modified from this snippet): * The part containing @onlyonce is needed so fx-autoconfig loads it just once, rather than spawn a new instance of the script every time a new firefox window is opened.
3. Clear startup cache: https://github.com/MrOtherGuy/fx-autoconfig?tab=readme-ov-file#deleting-startup-cache
4. You may need to toggle the script. You can go to Menu Bar > Tools > userScripts.

Script

// ==UserScript==
// @onlyonce
// ==/UserScript==

// Script from here:  https://gist.github.com/jscher2000/ad268422c3187dbcbc0d15216a3a8060?permalink_comment_id=3259657#gistcomment-3259657
setInterval(() => {
    /*
       Code to paste and run in the Browser Console
       Requires devtools.chrome.enabled => true in about:config
       Tested in Firefox 68.0.1 on Windows
    */

    // Create references to APIs we'll use
    var ss = Cc["@mozilla.org/content/style-sheet-service;1"].getService(Ci.nsIStyleSheetService);
    var io = Cc["@mozilla.org/network/io-service;1"].getService(Ci.nsIIOService);
    var ds = Cc["@mozilla.org/file/directory_service;1"].getService(Ci.nsIProperties);
      
    // Get the chrome directory in the current profile
    var chromepath = ds.get("UChrm", Ci.nsIFile);

    // Specific file: userChrome.css or userContent.css
    chromepath.append("userChrome.css");

    // Morph to a file URI
    var chromefile = io.newFileURI(chromepath);

    // Unregister the sheet
    if(ss.sheetRegistered(chromefile, ss.USER_SHEET)){
      ss.unregisterSheet(chromefile, ss.USER_SHEET);
    }

    // Reload the sheet
    ss.loadAndRegisterSheet(chromefile, ss.USER_SHEET);
}, 1000)

OC by @TheTwelveYearOld@lemmy.world

Source https://lemmy.ca/comment/20502019

Modlog https://photon.lemmy.world/modlog?user=463551

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@Luci@lemmy.ca

Less than two weeks after the November release, Raspberry Pi OS received its December update with a collection of usability improvements, desktop refinements, and important stability fixes.

The release introduces a safe-eject mechanism for USB-connected HDD and NVMe drives, allowing users to remove external storage without risking data corruption. The Labwc desktop also gains a new Alt-F2 shortcut for opening the run dialog, extending its keyboard-driven workflow.

Moreover, the update adjusts how the Screens control panel behaves by no longer generating a default kanshi configuration file on launch, ensuring that existing user configurations are not unintentionally overwritten.

Less than two weeks after the November release, Raspberry Pi OS received its December update with a collection of usability improvements, desktop refinements, and important stability fixes.

The release introduces a safe-eject mechanism for USB-connected HDD and NVMe drives, allowing users to remove external storage without risking data corruption. The Labwc desktop also gains a new Alt-F2 shortcut for opening the run dialog, extending its keyboard-driven workflow.

Moreover, the update adjusts how the Screens control panel behaves by no longer generating a default kanshi configuration file on launch, ensuring that existing user configurations are not unintentionally overwritten.

Developers behind Redox OS, the original open-source operating system written from scratch in the Rust programming language, have ported Wayland to it with initially getting the Smallvil Wayland compositor up and running along with the Smithay framework and the Wayland version of the GTK toolkit.

The Redox OS project published their November 2025 status update where one of their main accomplishments for the past month is getting these initial Wayland components up and running on it. Before getting too excited though, they note that the Wayland compositor's performance is "not adequate" and thus more work to do on their Wayland support but an exciting first milestone

Pebble, the e-ink smartwatch with a tumultuous history, is making a move sure to please the DIY enthusiasts that make up the bulk of its fans: Its entire software stack is now fully open source, and key hardware design files are available too.

Pebble creator Eric Migicovsky announced the move on Monday in a blog post and video detailing the changes his reborn Pebble watchmaking firm has undertaken, and they're considerable.

I have seen folks talk about a pain point for using FF (or forks) being related to YouTube being super slow. The about:config settings the article mentions did seem to lead to YouTube loading faster on both my FF and Zen-Browser installs. So maybe this might help for others that specifically don't like to use FF as their main browser because of YouTube.

For those that just want the settings:

gfx.webrender.compositor.force-enabled (set to true and restart FF)

If on AMD GPU, this extra setting is supposed to help reduce CPU usage:

media.wmf.zero-copy-nv12-textures-force-enabled (set to true and restart FF)

The mailing list link

AWS engineers have been working on Linux kernel improvements to KVM's VMX code for enhancing the unamanged guest memory when dealing with nested virtual machines. The improved code addresses some correctness issues as well as delivering wild performance improvements within a synthetic benchmark.

On Friday Amazon/AWS engineer Fred Griffoul sent out the latest patches to the KVM nVMX code for improving the performance of unmanaged guest memory.