span.cke_button__save_icon {
  background: url(<%= asset_data_uri('ckeditor/plugins/effective_regions/icons/save.png') %>);
}

span.cke_button__save_icon.saving {
  background: url(<%= asset_data_uri('ckeditor/plugins/effective_regions/icons/saving.png') %>);
}

span.cke_button__exit_icon {
  background: url(<%= asset_data_uri('ckeditor/plugins/effective_regions/icons/exit.png') %>);
}