.img-slices{
  display:flex;
  position:relative;
  --sliceCount: 10; /*default, adjust in inline style prop*/
}
.img-slices img:nth-child(1){
  width: 30em;
  max-width: 100%;
  height: auto;
}
.img-slices img:nth-child(2){
  position:absolute;
  top: 0;
  left: 0;
  
   /*match size first image*/
  width: 100%;
  height: 100%;
  object-fit: cover;

  /*  mask  */
  --sliceSize: calc(100% / var(--sliceCount));
  --maskGradient: repeating-linear-gradient(to right, transparent 0px var(--sliceSize), black var(--sliceSize) calc(var(--sliceSize) * 2));
  -webkit-mask-image: var(--maskGradient);
  mask-image: var(--maskGradient);
}

/* for demo */
body{
  box-sizing: border-box;
  margin: 0;
  padding: 2em;
  height: 100vh;
  display:grid;
  place-items: center;
  background-color:#111;
}