in the styles.css file, you have the following selectors:
.prev {
background: url("../images/left-arrow.png") no-repeat scroll center center rgba(0, 0, 0, 0);
cursor: pointer;
height: 40px;
left: 0;
position: absolute;
top: 140px;
width: 40px;
}
.next {
background: url("../images/right-arrow.png") no-repeat scroll center center rgba(0, 0, 0, 0);
cursor: pointer;
height: 40px;
position: absolute;
right: 0;
top: 140px;
width: 40px;
}
that are conflicting with the previous and next styles defined by the gallery.
the position absolute setting is causing the previous button to move the thumbnail strip