doc/dev/plugins/problems/scss/_carousels.scss

// Carousels
.carousel {
  background: $bg-color;
  display: block;
  overflow: hidden;
  position: relative;
  width: 100%;
  -webkit-overflow-scrolling: touch;
  z-index: $zindex-0;

  .carousel-container {
    height: 100%;
    left: 0;
    position: relative;
    &::before {
      content: "";
      display: block;
      padding-bottom: 56.25%;
    }

    .carousel-item {
      animation: carousel-slideout 1s ease-in-out 1;
      height: 100%;
      left: 0;
      margin: 0;
      opacity: 0;
      position: absolute;
      top: 0;
      width: 100%;

      &:hover {
        .item-prev,
        .item-next {
          opacity: 1;
        }
      }
    }

    .item-prev,
    .item-next {
      background: rgba($gray-color-light, .25);
      border-color: rgba($gray-color-light, .5);
      color: $gray-color-light;
      opacity: 0;
      position: absolute;
      top: 50%;
      transition: all .4s ease;
      transform: translateY(-50%);
      z-index: $zindex-1;
    }
    .item-prev {
      left: 1rem;
    }
    .item-next {
      right: 1rem;
    }
  }

  .carousel-locator {
    &:nth-of-type(1):checked ~ .carousel-container .carousel-item:nth-of-type(1),
    &:nth-of-type(2):checked ~ .carousel-container .carousel-item:nth-of-type(2),
    &:nth-of-type(3):checked ~ .carousel-container .carousel-item:nth-of-type(3),
    &:nth-of-type(4):checked ~ .carousel-container .carousel-item:nth-of-type(4) {
      animation: carousel-slidein .75s ease-in-out 1;
      opacity: 1;
      z-index: $zindex-1;
    }
    &:nth-of-type(1):checked ~ .carousel-nav .nav-item:nth-of-type(1),
    &:nth-of-type(2):checked ~ .carousel-nav .nav-item:nth-of-type(2),
    &:nth-of-type(3):checked ~ .carousel-nav .nav-item:nth-of-type(3),
    &:nth-of-type(4):checked ~ .carousel-nav .nav-item:nth-of-type(4) {
      color: $gray-color-light;
    }
  }

  .carousel-nav {
    bottom: $layout-spacing;
    display: flex;
    justify-content: center;
    left: 50%;
    position: absolute;
    transform: translateX(-50%);
    width: 10rem;
    z-index: $zindex-1;

    .nav-item {
      color: rgba($gray-color-light, .5);
      display: block;
      flex: 1 0 auto;
      height: $unit-8;
      margin: $unit-1;
      max-width: 2.5rem;
      position: relative;

      &::before {
        background: currentColor;
        content: "";
        display: block;
        height: $unit-h;
        position: absolute;
        top: .5rem;
        width: 100%;
      }
    }
  }
}

@keyframes carousel-slidein {
  0% {
    transform: translateX(100%);
  }
  100% {
    transform: translateX(0);
  }
}

@keyframes carousel-slideout {
  0% {
    opacity: 1;
    transform: translateX(0);
  }
  100% {
    opacity: 1;
    transform: translateX(-50%);
  }
}