AdminLTE/build/less/carousel.less

/*
 * Component: Carousel
 * -------------------
 */
.carousel-control {
  background-image: none!important;
  > .fa {
    font-size: 40px;
    position: absolute;
    top: 50%;
    z-index: 5;
    display: inline-block;
    margin-top: -20px;
  }
}