Bringing sexy curves back to Firefox Photon AND Proton.
Because all you sexy Firefox users deserve something sexier than ugly, blocky square. (Who wants to be square, right?)
This is a NEW release that supports Firefox Proton (version 89+). If you are running an older version of Firefox with Photon, please visit this link.
This is regular used and tested by me in these following configurations:
- Firefox Developer Edition on Dark Theme + Windows 10 on Dark Theme.
 - Firefox Developer Edition on Default Theme + MacOS on Dark Theme.
 
Since Firefox 57+, the only way to customize your browser UI is through userChrome.css. Learn more here.
- Go to your Firefox browser, type 
about:configin your url bar. - Search for 
toolkit.legacyUserProfileCustomizations.stylesheetsand set it totrue - Type 
about:profilesin your url bar. - Under the profile that is in use (The message is something like 
This is the profile in use and it cannot be deleted.), clickOpen Folderon theRoot Directoryrow. - If that folder does not have a 
chromefolder, create a folder, name itchrome. - In the 
chromefolder, create a file nameduserChrome.css - Determine what Firefox theme you are using:
- Click the icon with 3 lines on the top right corner to open the context Menu.
 - Select 
Customize. - At the bottom left of your screen, select 
Themes. - Choose or determine which theme you want to use, they can either be 
Dark,Default, orLight. 
 - Copy and paste the code that matches your Firefox theme: Dark, Default, Light into your 
userChrome.cssfile that you have created.
WARNING: Newer versions of Firefox with Mojave or Windows 10 Dark Mode will cause Firefox to use theDarktheme by default. In this case, you should use the userChrome-dark.css theme. - Restart Firefox and enjoy some sexy curves :D
 
If you are using the Default Theme but your MacOS is using the Dark Theme, you can go to about:config -> search for ui.systemUsesDarkTheme and ADD (click the '+' sign) a Number. Set the value to 0. Restart the browser.
Fell free to create an issue and I'll see what I can do. However, I'm unable to guarantee quick (or any) responses as this project is in maintenance mode.
Please follow these instructions created by a helpful Redditor: https://www.reddit.com/r/FirefoxCSS/comments/bzd5dz/help_with_australis_css/
Make sure that your file extension for userChrome.css is correct. Most likely a problem for Windows, refer to this issue.


