Minor styling issues

[IgorAlexey]

The Firefox Colors extension appears to be causing the title bar buttons to revert to the unmodified svg image: No solution other than deactivating the extension was found... Which causes a weird palette mismatch:

The TST grip line seems inconsistent on different systems for some reason, is there a way to fix it? Edit: Ideally it should not be there? :thinking:

Overall the theme works amazing! And does not have other issues.