Collection of userstyles affecting the browser

This repository contains various styles to modify appearance of Mozilla Firefox. These stylesheets are mostly self-contained and can be mixed with each other somewhat freely, but there are no promises about compatibility with third-party styles.

In the case that a particular style relies on another style, the fact will be noted at the start of the file that requires so.

Stylesheets in this repository are tested only on Windows 10 and to a lesser amount on Linux. Most of them should also work on OSX and Windows7, but there may be wrong behavior especially when native widgets such as window titlebar or window control buttons are being styled.

As an overview, you will make Firefox load two special stylesheets - userChrome.css and userContent.css. Doing so requires setting a specific preference (see below) and then creating those files inside your Firefox user profile.

The setup is quite straightforward with the exception of how to find the profile folder so pay attention to that.

Go to about:config and set the pref toolkit.legacyUserProfileCustomizations.stylesheets to true

After you set this pref, Firefox will try to load userChrome.css and userContent.css - but those files don't exist yet so now let's create them.

First, find your profile folder. While Firefox is running, go to about:support and find a Profile folder row near the top - there should also be a button labeled "Open folder" next to it. Clicking that button should open the folder in your file manager.

NOTE: On some Firefox versions clicking that button may open the profiles folder which houses all your profiles. In that case, navigate into the specific folder you wish to modify. about:support should still show the correct folder name so refer to that if you need to figure out the what folder you need to open.

The real profile folder should have files like prefs.js and places.sqlite If you see those two files in the folder, then great! You found the profile folder! Now lets actually create those stylesheet files.

Note: only userChrome.css is mentioned in this section for brevity, but everything regarding that will also apply to userContent.css

Firefox loads userChrome.css from <profileFolder>/chrome/userChrome.css. That chrome-folder or the stylesheet files do not exist by default.

<profile_folder>
|_ chrome
|   |_ userChrome.css
|   |_ userContent.css
|_ extensions
|_ prefs.js
...
all other profile folders and files
...

The files themselves are only separated to chrome and content sub-folders. Files have a one or more tag applied to them as listed in tags.csv file.

You can browse the tag-categorized files by using this UI

Stylesheets are divided in to chrome and content folders. Firefox loads userChrome.css into the browser UI and it loads userContent.css into the content documents like web pages and built-in or extension pages.

Use stylesheets under "chrome" in userChrome.css

Use stylesheets under "content" in userContent.css

The above is not a technical requirement but the particular styles generally won't do anything when loaded in wrong context.

You can import the stylesheets with @-rule import like this:

@import url("path/filename.css");

A good habit would be to load each separate style without modifications using @import statements, and then apply your own modifications in userChrome.css after all imports. This makes it easier for you to update the files from the repository since your modifications will be preserved.

Example userChrome.css:

@import url(chrome/tab_close_button_always_on_hover.css);
@import url(chrome/tab_loading_progress_throbber.css);
@import url(chrome/button_effect_scale_onclick.css);

:root{
  --toolbar-bgcolor: rgb(36,44,59) !important;
  --uc-menu-bkgnd: var(--toolbar-bgcolor);
  --arrowpanel-background: var(--toolbar-bgcolor) !important;
  --autocomplete-popup-background: var(--toolbar-bgcolor) !important;
  --uc-menu-disabled: rgb(90,90,90) !important;
  --lwt-toolbar-field-focus: rgb(36,44,59) !important;
}

Note that all @import rules need to be placed before any other rules in the file, including @namespace rules. Additionally, the order of imported files is just as important as the order of rules within one file.

I would strongly advice using @import to include styles instead of copying contents directly to userChrome.css even with just a few file "components". The technical reason for this is that some files rely on @namespace rules and those only apply on file level such that a @namespace applies to every selector in that file (and in that file only). On top of that, @imports make managing multiple files much easier.

Import any *_patch.css files after their base stylesheet. Import the shared window_control_support.css before other stylesheets.

Additionally, you are advised to import theme_ files before any other modules.

** NOTE ** Theme files are mostly out-of-date as of 2020-05-22

Stylesheets prefixed with theme_ require theme_color_variables.css to be imported.

Example userChrome.css resulting in rather complete dark blueish-grey UI:

@import url(theme_color_variables.css);
@import url(theme_sidebar.css);
@import url(theme_toolbars.css);
@import url(theme_popups_and_menus.css);

/* Your other rules here */

You can use individual modules from theme such as to only include popups_and_menus. But it would still be required that you import the theme_color_variables.css or you'll have to manually edit all the colors.