Bootstrap/scss/_carousel.scss

// Wrapper for the slide container and indicators
.carousel {
  position: relative;
}

.carousel-inner {
  position: relative;
  width: 100%;
  overflow: hidden;
}

.carousel-item {
  position: relative;
  display: none;
  width: 100%;

  @include if-supports-3d-transforms() {
    @include transition(transform .6s ease-in-out);
    backface-visibility: hidden;
    perspective: 1000px;
  }
}

.carousel-item.active,
.carousel-item-next,
.carousel-item-prev {
  display: block;
}

.carousel-item-next,
.carousel-item-prev {
  position: absolute;
  top: 0;
}

// CSS3 transforms when supported by the browser
@include if-supports-3d-transforms() {
  .carousel-item-next.carousel-item-left,
  .carousel-item-prev.carousel-item-right {
    transform: translate3d(0, 0, 0);
  }

  .carousel-item-next,
  .active.carousel-item-right {
    transform: translate3d(100%, 0, 0);
  }

  .carousel-item-prev,
  .active.carousel-item-left {
    transform: translate3d(-100%, 0, 0);
  }
}


//
// Left/right controls for nav
//

.carousel-control {
  position: absolute;
  top: 0;
  bottom: 0;
  width: $carousel-control-width;
  font-size: $carousel-control-font-size;
  color: $carousel-control-color;
  text-align: center;
  opacity: $carousel-control-opacity;
  // We can't have a transition here because WebKit cancels the carousel
  // animation if you trip this while in the middle of another animation.

  // Hover/focus state
  @include hover-focus {
    color: $carousel-control-color;
    text-decoration: none;
    outline: 0;
    opacity: .9;
  }
}
.carousel-control-prev {
  left: 0;
}
.carousel-control-next {
  right: 0;
}

// Icons for within
.carousel-control-prev-icon,
.carousel-control-next-icon {
  position: absolute;
  top: 50%;
  z-index: 5;
  display: inline-block;
  width: $carousel-icon-width;
  height: $carousel-icon-width;
  margin-top: -($carousel-icon-width / 2);
  font-family: serif;
  line-height: 1;
  background: transparent no-repeat center center;
  background-size: 100% 100%;
}
.carousel-control-prev-icon {
  left: 50%;
  margin-left: -($carousel-icon-width / 2);
  background-image: $carousel-control-prev-icon-bg;
}
.carousel-control-next-icon {
  right: 50%;
  margin-right: -($carousel-icon-width / 2);
  background-image: $carousel-control-next-icon-bg;
}


// Optional indicator pips
//
// Add an unordered list with the following class and add a list item for each
// slide your carousel holds.

.carousel-indicators {
  position: absolute;
  bottom: 10px;
  left: 50%;
  z-index: 15;
  width: $carousel-indicators-width;
  padding-left: 0;
  margin-left: -($carousel-indicators-width / 2);
  text-align: center;
  list-style: none;

  li {
    position: relative;
    display: inline-block;
    width: $carousel-indicator-width;
    height: $carousel-indicator-height;
    text-indent: -999px;
    cursor: pointer;
    background-color: rgba($carousel-indicator-active-bg, .5);

    // Use pseudo classes to increase the hit area by 10px on top and bottom.
    &::before {
      position: absolute;
      top: -10px;
      left: 0;
      display: inline-block;
      width: 100%;
      height: 10px;
      content: "";
    }
    &::after {
      position: absolute;
      bottom: -10px;
      left: 0;
      display: inline-block;
      width: 100%;
      height: 10px;
      content: "";
    }
  }

  .active {
    background-color: $carousel-indicator-active-bg;
  }
}


// Optional captions
//
// Hidden by default for smaller viewports.

.carousel-caption {
  position: absolute;
  right: ((100% - $carousel-caption-width) / 2);
  bottom: 20px;
  left: ((100% - $carousel-caption-width) / 2);
  z-index: 10;
  padding-top: 20px;
  padding-bottom: 20px;
  color: $carousel-caption-color;
  text-align: center;
}


//
// Responsive variations
//

@include media-breakpoint-up(sm) {
  // Scale up the controls a smidge
  .carousel-control-icon-prev,
  .carousel-control-icon-next {
    width: $carousel-control-sm-up-size;
    height: $carousel-control-sm-up-size;
    margin-top: -($carousel-control-sm-up-size / 2);
    font-size: $carousel-control-sm-up-size;
  }
  .carousel-control-icon-prev {
    margin-left: -($carousel-control-sm-up-size / 2);
  }
  .carousel-control-icon-next {
    margin-right: -($carousel-control-sm-up-size / 2);
  }

  // Show and left align the captions
  .carousel-caption {
    right: ((100% - $carousel-caption-sm-up-width) / 2);
    left: ((100% - $carousel-caption-sm-up-width) / 2);
    padding-bottom: 30px;
  }

  // Move up the indicators
  .carousel-indicators {
    bottom: 20px;
  }
}