Superfish Menu Plugin border left problem

Superfish Menu Plugin border left problem

I am using superfish plugin for displaying my menu. Everything is working but I have a problem with menu divider such as below:

.sf-menu a {
    border-left:    5px solid #fff;
    padding:         .3em 1em;
    text-decoration:none;
}


As the border applies to all anchor tags, the first menu item on the left side and the child nodes under each menu item also will have border applied. But I want the divider to appear in between the top level menu items only. Can someone direct me here. Thanks.