'unknown word' error when using less preprocessor

[minnieoo]

i have 'unknown word' error when using less preprocessor. i am user userCss option. the mixin refuses to work, but using these same settings with less & mixins works fine on OTHER styles, i even tried copying other styles where it works, and just replacing the inner css and still this error. here is a link to the user style so you can take a look: https://userstyles.world/style/13516/rainbowbin-not-working

[tophf]

Our linters can't check some of the advanced preprocessor features yet.
For now, you can collapse the Issues panel or disable CSS Linter option to hide the error.

[minnieoo]

i'm confused, it works fine with no errors on other styles though

[tophf]

I guess those styles don't use this particular feature.

[minnieoo]

but they do use mixins

[tophf]

I can't guess further without seeing the actual code.

[tophf]

BTW Your current style can't be parsed by LESS because it doesn't support multiple selectors inside :is, it's a bug in the preprocessor as seen in https://lesscss.org/less-preview/, so you'll have to use a workaround e.g. escape the comma or something else.