Add background and highlight descrtiption in popup

CSS Codes Photo Gallery
1

Add this code to the Custom CSS field on your Photo Gallery widget’s Style tab:

.global-styles, .fslightbox-caption-body {
  background: rgba(0, 0, 0, 0.5);
  padding: 20px;
}
.global-styles, .fslightbox-caption-title {
  font-size: 24px;
  font-weight: 900;
}
.global-styles, .fslightbox-caption-description {
  font-size: 20px;
  font-weight: 400;
}