.slider {
  list-style: none;
  position: relative;
  width: 100vw;
  display: flex;
  justify-content: center;
  align-items: center;
}

.slider li {
  position: absolute;
  opacity: 0;
  background: #fff;
  transition: opacity 0.5s;
}

.slider li img {

  height: 300px;
}

.slider li:first-child {
  opacity: 1;
}

.slider li:target {
  opacity: 1; /*mostramos la que le hemos dado clic */
}