Fix marker for n-level menus on sidebar

The marker.png is style-broked for n-level menus on sidebar on latest Firefox in Linux.

To fix replace line 448 in style.css:

From: background: url("../images/marker.png") no-repeat scroll 4px center rgba(0, 0, 0, 0);
To: background: url("../images/marker.png") no-repeat scroll 4px 5px rgba(0, 0, 0, 0);

Thanks for great Themes!