.ruler-gallery {
  min-width: 100%;
  margin: auto;
}
.ruler-gallery .grid-item {
  float: left;
  margin: 10px;
}
.ruler-gallery .grid-item img{
  min-width: 100%;
  height: auto;
}
.ruler-gallery.columns-2 .grid-item { width: calc(50% - 20px); }
.ruler-gallery.columns-3 .grid-item { width: calc(33.33% - 20px); }
.ruler-gallery.columns-4 .grid-item { width: calc(25% - 20px); }