Gallery in disorder after editing thumbs.

I have this problem (see topic) on http://www.vaneis.nl/galerij/model-fotografie-2/

See this closed topic: http://wordpress.org/support/topic/plugin-nextgen-gallery-thumbnails-in-disorder-2nd-row-shows-just-one-image

But could find a solution in this forum or elswhere,
( I tried the change the *.css

.ngg-thumbnail img {
background-color:#FFFFFF;
border:1px solid #A9A9A9;
margin:4px 0px 4px 5px;
padding:4px !important;
position:relative;

But that makes no changes in the gallery. )
Any help appriciated.

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