>>5306
>Is it a wincel thing?
ah, indeed it is - it looks like waterfox ships with a special userChrome.css that's enabled by default. it includes a rule that forces --input-color to be a certain value based on the OS, and it only has rules for mac and windows, so I wasn't seeing it on linux. the rule is !important as well, so the only way to work around it on my end would be to change the variable name across all our CSS.
if that rule was only intended to modify the styling on built-in waterfox pages, like the settings page, then I'd consider this to be a defect on their side. if the intent is to use certain variable names like --input-color as an informal standard in order to override theming for websites (unlikely), then it's working as intended.
at any rate, you can disable the userChrome by changing this option (found on the "look and feel" page of settings) to "disable waterfox theme customizations". if you want to keep the other customizations that it makes to the browser's appearance, you might need to make your own custom copy of the included userChrome and then remove the offending !important rule shown in your screenshot.