Unpublished comment style is not applied

Hello,

I'd like to create a custom style to easily distinguish comments which have to be published from those which have been already published.

There's a file /css/comments.css which has something like this in line 39:

.comment-unpublished /* Unpublished comments */ {
  background-color: green;  /* Drupal core uses a #fff4f4 background */
}

However, when I place that definition it is not displayed at all, although I am sure to have emptied cache (in fact If I change lines above .comment.even and .comment.odd the styles are displayed perfectly).

Additionally the "unpublished" label also ignores the definition in line 43

.comment-unpublished div.unpublished /* The word "Unpublished" displayed underneath the content. See also the div.unpublished declaration in the nodes.css. */ {
  color: red;
}

Am I missing something or is this a bug?

Thanks