html, body {
  width: 100%;
  height: 100%;
  padding: 0;
  margin: 0;
}

body {
  background-color: black;
  display: flex;
  justify-content: center;
  align-items: center;
  animation: filter-animation 1s infinite;
}

#download {
  display: none;
  position: absolute;
  bottom: 10px;
  right: 10px;
}

#download.visible {
  display: block;
}

@keyframes filter-animation {
    0% {
      filter: hue-rotate(0deg);
    }
    
    25% {
      filter: hue-rotate(360deg);
    }
	
	50% {
      filter: hue-rotate(180deg);
    }
	
	75% {
      filter: hue-rotate(360deg);
    }
    
    100% {
      filter: hue-rotate(0deg);
    }
  }