Is it possible to center thumbnails?

I’m using GPP Slideshow 1.3.2 and have not been able to get the thumbnails to be centered. Can someone PLEASE help me with this?

I’ve tried adding the following to my custom CSS:
.gpp_slideshow_thumbnails {
margin-left: auto !important;
margin-right: auto !important;
width: 99% !important;
text-align: center !important;
}

I tried applying the above to a few other classes, too, but nothing will make those little buggers center up 😀 Any suggestions would be greatly appreciated!

http://wordpress.org/plugins/gpp-slideshow/