.slideshow-wrapper {
  position: relative;
}

.slideshow-wrapper .overlay{
  display: block; 
  position: absolute;
  width: 100%;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 1;
  opacity: var(--overlay-opacity);
  background: var(--overlay-background);
}