.content-overlay {
background: rgba(0,0,0,0.2);
  position: absolute;
  height: 99%;
  width: 100%;
  left: 0;
  top: 0;
  bottom: 0;
  right: 0;
  opacity: 0;
  -webkit-transition: all 0.4s ease-in-out 0s;
  -moz-transition: all 0.4s ease-in-out 0s;
  transition: all 0.4s ease-in-out 0s;
}

.kl-card-grid__card:hover .content-overlay {
  opacity: 1;
}