Show an icon in masonry, depending on category

on the link of the masonry items – you have a class: portfolio_entries-xyz the xyz is the portfolio “category” ( this is actually a taxonomy)

you can place it in a pseudo-container like:
see here: https://webers-testseite.de/pureinstall/portfolio-masonry/
(this was originally a help to place the selection next to the masonry.)

.portfolio_entries-buecher .av-masonry-outerimage-container:before {
  content:"";
  width: 100%;
  height: 100%;
  position: absolute;
  background-image: url(https://webers-testseite.de/pureinstall/wp-content/uploads/Buecher.png);
  background-repeat: no-repeat;
  background-size: 100px;
  background-position: center 30%;
  z-index: 2;
}

and: on posts and categories the class is: category-xyz the category name is the xyz