ul.thumbnails.image_picker_selector {
  display: grid !important;
  grid-template-columns: repeat(2, 1fr);
  gap: 10px;
  justify-content: center;
  list-style: none;
  padding: 0;
  margin: 0;
}

ul.thumbnails.image_picker_selector li {
  display: flex;
  justify-content: center;
  align-items: center;
}