The issue is really that the media query parser fails to parse the inner queries and just gives a raw string for the expression, but it should be safe to remove extra spaces. I can't make it rmeove spaces inside () that way unfortunately :(
If you put a space, `{loose: true}` is going to parse them as word + paren instead of func. It doesn't impact correctness and i'm not really sure how to clean the ast, so let's just make the test pass. I haven't seen this anywhere in real code.
I wanted to see how hard it would be to add support for CSS inside of prettier. Turns out, it's not that hard. I spent a few hours printing post-css values and getting all the stylefmt unit tests to not throw.
Christopher Chedeau