Good question. The gallery is created by the NextGen gallery plugin and it is set to align to the left in its styling.
#four .ngg-galleryoverview {
text-align: center;
}
#four .ngg-gallery-thumbnail-box {
float: none;
display: inline-block;
}
#four .ngg-gallery-thumbnail{
float: none;
display: inline-block;
}
#four .widget {
margin-left: 0;
margin-right: 0;
}
Not trying to pry here, but is there a particular reason why you went with the NextGen Gallery plugin? It’s kind of a left-over from the era when WordPress didn’t have native image galleries. Unless the current site is already locked into that mess, it’s usually good to avoid it.
Bill