Return to Revisions

To add CSS to node edit pages you can use hook_form_alter. Then check the $form_id to localize changes to desired node form(s) and add you call to drupal_add_css().

Example:

function hook_form_alter(&$form, &$form_state, $form_id) {
  if ($form_id == "xxx") {
    drupal_add_css();
  }
}