Sorry. I should have said that I looked at the development tools and I couldn't find a class for it. Not even one of the random classes.
But now I look again and I see there is .cm-variable-2 and that does it. But I don' know how to be sure that this class isn't also used for something else. I guess it may be unknowable. It seems to also style ordered lists also. [EDIT: and checkbox lists]
Thanks! Sorry, I should have tried harder.