.green-rectangle{
  width: 100%;
  height: 100px;
  background-color: green;
  color: white;
  text-align: center;
  font-size: 40px;
  padding: 30px;
  opacity: 0;
  transition: 1s;
  margin-top:40px;

}

 .show{
  opacity: 1 !important
}

.spacing{
  height: 350px
}

const controller = new ScrollMagic.Controller();

const scene = new ScrollMagic.Scene({
  triggerElement: '.green-rectangle'
})
.addIndicators()
.setClassToggle('.green-rectangle', 'show')
.addTo(controller);