.full_size_gallery {
  position: relative;
}
.full_size_gallery > .img_preview {
  position: absolute;
  top: 0;
  left: 0;
  overflow: hidden;
  opacity: 0;
  visibility: hidden;
  transition: opacity 300ms ease, visibility 300ms ease;
}
.full_size_gallery > .img_preview.active {
  opacity: 1;
  visibility: visible;
}
.full_size_gallery_navigation .img_preview.active {
  box-shadow: 0 0 8px rgba(0,0,0,0.5);
}