Template:PopupImage/styles.css

.popup-container {
  display: inline-block;
  position: relative;
}
.popup-text {
  cursor: pointer;
}
.popup-image {
  opacity: 0;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  visibility: hidden;
  z-index: 999;
  transition: 55ms ease-in;
}
.popup-container:hover .popup-image {
  opacity: 1;
  visibility: visible;
}