[[Module:compound/templates]]: derivsee

But what could would that do? At best we would just do what the current class= argument to the parser function does anyway.

For example, override script CSS for the category name line (assuming it has a different class from that of the entries. I have not checked.

That's what the class= argument does.

Does the class argument apply to just the category name line, or to the whole thing?

I don't know. But it's what is used to apply the sc= parameter of the template currently.

I looked into it and the class "CategoryTreeLabelCategory" is used for the category link, while "CategoryTreeLabelPage" is used for the entry links. So these are the ones we want to target. I'm not a CSS expert, but hopefully someone can figure out how to override "CategoryTreeLabelCategory" to inherit the "Latn" class.