Firefox Quantum Rounded Tabs v. 1.1

What it does

This one-simple-file solution reshapes Firefox Quantum's default tabs by:

• removing the bold line at the top of the selected tab;
• rounding the top corners;
• slightly separating and outlining the tabs.

See screenshots > the Silky Blue example (click Download for a bigger display). That example has a light background, but you can also have a dark one. See the other examples and the CSS file for that (customization).

The CSS file also colors the Bookmarks icons orange and removes 3 of the 4 objects from the address bar. The applicable rules are at the bottom of the file, self-explanatory and customizable as well.

Preparations before installation

1. Download and unzip the package, whereby the userChrome.css file is what it's all about.
2. Make Windows show its file extensions if it doesn't do that already. See https://www.howtogeek.com/205086/beginner-how-to-make-windows-show-file-extensions/.
3. At first, select a light extra Firefox theme: hamburger menu > Customize > Themes. The theme Silky Blue can be downloaded from the Firefox Themes site.
4. Type about:config in the Firefox address bar and press Enter. Search for toolkit.legacyUserProfileCustomizations.stylesheets. If there is such a rule, check that it's set to true. If no such rule, simply continue with the installation.

Installation

1. Type about:support in Firefox's address bar and press Enter.
2. On the appearing page, you will see 'Profile folder' in the left column. Click 'Open folder'.
3. In the appearing window, right-click and click 'New folder'. Give the folder the name chrome.
4. Copy or move the userChrome.css file to that folder.
5. Close & restart Firefox and enjoy your new interface. :-)

Going back to default

Simply delete the file or the whole chrome folder and restart Firefox.

Customization

You have to be very careful with that, even if you know CSS. The problem is that Firefox's internal CSS rules sometimes differ from web CSS rules. And its logic regarding classes, IDs and layers differs from (valid) HTML as well.

But you can and should change the tab text color to a light one if you want a dark theme. For CSS color names and codes, see https://www.w3schools.com/colors/colors_names.asp. The variables in the file that you can change without risk are followed by the comment 'customizable'. To open the CSS file after being installed, right-click > Open with > Notepad.

Problems and other comments

If you would encounter a problem and have a Github account, please start a New Issue. Other comments are welcome at f [dot] conijn [at] conijnconsultancy [dot] com.

Change log

v. 1.1: Split the tab text color coding into two parts, one for all tabs and one for only the selected tab.