[Bug]: Cannot get a userChrome.css theme working

[scrubborn]

Pre-Submission Checklist

• I have checked the existing/closed issues to ensure this issue has not already been reported.
• I am using the latest supported version of the browser.
• I have tried disabling all browser extensions/add-ons to rule out interference from these.
• I have tried clearing the browser cache and cookies.
• I have checked with a new profile and the issue still occurs.
• I have provided detailed step-by-step instructions on how to reproduce the issue.
• I have included relevant screenshots or console outputs.
• I have checked that this problem is not occurring in the latest version of Firefox ESR.
• This issue is specific to this browser and does not occur in other browsers.

Bug Summary

The following theme -

https://gitgud.io/wackyideas/aero-userchrome

Will not apply no matter what I do, when the same steps work on firefox. I originally noticed this on Firedragon but was able to reproduce on current version Floorp.

Reproduction Steps

1. Create a new profile
2. Add my chrome folder from the gitgud rep into the proper directory
3. Ensure that “toolkit.legacyUserProfileCustomizations.stylesheets” was set to true
4. Edit the userChrome.css per the theme instructions
   @import url("Echelon/userChrome.css"); @import url("Aero/Echelon.css");
5. Relaunch Floorp

Expected Behavior

The theme should activate.

Actual Behavior

No theme changes occur.

Screenshots

Browser Version

v11.21.0

Operating System

Garuda Linux

Additional Context

No response

[black-ish]

You can remove the @import lines and just put the .css files into the CSS folder.
They should load, without needing any @import lines in the userchrome.css.

[scrubborn]

That seems to have gotten me further, though I am having rendering issues with this theme. I suppose at that point I can try and ask the maintainer of the theme, as floorp is atleast attempting to load the CSS now. Thank you.