Path to grippie.png returns 404 error

If the module is installed to sites/all/themes/genesis_webx, the following CSS in genesis_webx.css causes a 404 error when trying to load grippie.png

.resizable-textarea .grippie {
  background: #B3B270 url(../../misc/grippie.png) no-repeat scroll center 2px;
  border-color: #75804D;
}

the path resolves to /sites/all/misc/grippie.png

changing the path to '/misc/grippie.png' solves the problem for sites with Drupal installed at the root level.

The grey-on-green is difficult to see though. A custom grippie.png modified to a darker colour would probably look better.