The "Check books" error for malordered CSS rules says:
Expected selector "X" to come before selector "Y"
However, the associated details only give the position of rule X, not rule Y (compare with the error for mismatched tags, which gives the position of both tags).
Would it be possible to show the position of both selectors in the error message to make it easier to locate Y? (Or better still, since the checker can obviously recognise the expected order of rules, have an autofix option which reorders all the rules automatically?)