There are no borders on your site, you have only shadow on hover. If you want to disable this, edit module file style.css and delete this:
Code:
#responsivelightbox img:hover, #responsivelightbox img:focus {
-webkit-box-shadow: 0 0 0.938em rgba( 0, 0, 0, .25 );
box-shadow: 0 0 0.938em rgba( 0, 0, 0, .25 );
}
Regards,
Milos
