.field--type-image .field__item {
  position: relative;
  display: inline-block;
}
.field--type-image .field__item:before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background-color: #79dea8;
  transform: scaleX(0);
  transform-origin: left;
  transition: all ease 0.4s;
  opacity: 1;
  z-index: 1;
}
.field--type-image .field__item.show:before {
  transform: scaleX(1);
}