.carousel {
  width: 250px;
  height: 650px;
  position: relative;
  overflow: hidden;
}

.carousel img {
  width: 100%;
  height: 100%;
  position: absolute;
  top: 0;
  left: 0;
  opacity: 0;
  transition: opacity 1s ease-in-out;
}

.carousel img.active {
  opacity: 1;
}