Nextgen Slideshow double border

I have a slideshow on my page: http://chagnon-br.com/our-projects/residential/additions/ with the following:
.slideshow {
border-style:inset;
border-color:grey;
border-width:5px;
margin-left: 20px;
margin-right: 20px;
margin-top: 0px;
margin-bottom: 0px;
text-align:center;
float:left;

How do I remove the inset border which seems to be around the margin area on the left and right

http://wordpress.org/extend/plugins/nextgen-gallery/