body,
html {
  width: 100%;
  height: 100%;
  font-family: Arial, sans-serif;
  overflow: hidden;
  margin: 0;
  font-size: 20px;
  background: #1d1d1d;
}

body {
  display: flex;
  align-items: center;
  justify-content: center;
}

.gallery {
  width: 640px;
  height: 480px;
  visibility: hidden;
}

.gallery img {
  width: 640px;
  height: 480px;
  position: absolute;
}

.dragger {
  width: 10px;
  height: 480px;
  background: red;
  opacity: 0.5;
  position: absolute;
}

.clipped {
  filter: saturate(0) contrast(1.5);
  clip-path: inset(0px 320px 0px 0px);
}

@media only screen and (max-width: 500px) {
  /* For mobile phones: quick and dirty */
  .gallery {
    transform: scale(50%);
    transform-origin: 0 0;
    position: relative;
    left: -20%;
  }
  body {
    display: block;
  }
}