.img-comp-container {
  position: relative;
  /* height: 400px; /*should be the same height as the images
  display: inline-block; /* Make the width of box same as image */
  width: 650px;
  left: 2px;
}

.img-comp-img {
  position: absolute;
  width: auto;
  height: auto;
  overflow: hidden;
}

.img-comp-img img {
  display: block;
  vertical-align: middle;
}

.img-comp-slider {
  position: absolute;
  z-index: 9;
  cursor: ew-resize;
  /*set the appearance of the slider:*/
  width: 16px;
  height: 16px;
  background-color: #2196F3;
  opacity: 0.7;
  border-radius: 50%;
}