Change Asterisk to Image

Hello,

I've read similar posts regarding the asterisk, and even tried a few. So far, the only thing that's worked for me is changing the COLOR of the asterisk, but my client has requested an image, not just a color change.

http://www.macmedspa.com/contact-us/ is the live site, and you can see the purple stars I've made per the code: .gfield_required {color: #861ede!important;}

I had previously tried:

.gform_wrapper .gfield_required {
    width:16px;
    height:16px;
    display: -moz-inline-stack;
    display: inline-block;
    zoom: 1;
    *display: inline;
    text-indent:-9000px;
    background-image:url(http://www.macmedspa.com/wp-content/uploads/2012/09/star.png);
    background-repeat:no-repeat
}

But that didn't work for me either. I'm hoping you can help? I'm a bit stuck.

Thank you in advance. :)

It finally worked for me - thanks Chris. :)

Great plugin, btw.