FRONTEND_MVC/assets/less/components/post/gallery.less

.gallery{
  display: flex;
  overflow: hidden;
  width: 100%;
  padding-bottom: 56.25%;
  position: relative;
  margin-bottom: 30px;
  img{
    width: 100%;
  }
  .splide__slide {
    opacity: 0.6;
    transition: .3s;
  }

  .splide__slide.is-active {
    opacity: 1;
  }
}