/* General layout */
.container {
  position: relative;
  max-width: 800px;
  height: auto;
  aspect-ratio: 6 / 4;
  display: grid;
  place-items: center;
  overflow: hidden;
}
/* Overlap the image containers, and stretch the images to fill the container */
div div {
  position: absolute;
  height: 100%;
  left: 0;
  right: 0;
}
img {
  height: 100%;
  object-fit: cover;
}
div div {
  position: absolute;
  height: 100%;
  left: 0;
  right: 0;
}
#left img {
  object-position: 0 0;
}
#right img {
  object-position: 100% 0;
}
/* Setup the `range` element */
input {
  --thumb-width: 17px;
  width: calc(100% + var(--thumb-width));
  z-index: 1;
}

/* Set the anchor position */
#right {
  left: anchor(--thumb center);
}

/* Attach the slider handle to the anchor*/
input::-webkit-slider-thumb {
  anchor-name: --thumb;
}
input::-moz-range-thumb {
  anchor-name: --thumb;
}
input::-ms-thumb {
  anchor-name: --thumb;
}