.photo-thumbnail-container {
  position: relative;
  display: inline-block;
}

.photo-thumbnail-overlay {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.3);
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transition: opacity 0.3s;
  border-radius: 6px;
  cursor: pointer;
}

.photo-thumbnail-container:hover .photo-thumbnail-overlay {
  opacity: 1;
}

.photo-thumbnail-overlay span {
  font-size: 24px;
  color: white;
}