More context in CSS error messages

[wheany]

This is not helpful:

Selector syntax error
  }
  -^

Especially when using CSS generated from less, when the link in the right hand column goes to the raw html source, without the generated CSS embedded in it

[wheany]

Similar non-helpful error message:

Unknown at-rule
  }
  -^

Even just adding Unknow at-rule: @doesnotexist with the above non-context would help in finding the rule (or in filtering it)