viewer.css

/* Code adapted from https://codepen.io/acash/pen/zzBVPW */

body{
    background-color: transparent;
  }
  /* make each piece of paper fall down like confetti */
  .paper1, .paper2, .paper3, .paper4, .paper5, .paper6, .paper7{
    width: 10px;
    height: 10px;
    position: fixed;
    top: -15px;
    box-shadow: 0px 0px 2px #444;
    -webkit-animation: floating 2s ease-in, rotating .5s ease-in-out infinite;
  }
  
  .paper1{
    background: #e83415;
  }
  .paper2{
    background: GreenYellow;
  }
  .paper3{
    background: #01dcf5;
  }
  .paper4{
    background: yellow;
  }
  .paper5{
    background: orange;
  }
  .paper6{
    background: #11D;
  }
  .paper7{
    background: Fuchsia;
  }
  
  @-webkit-keyframes floating{
    from {top: -15px}
    to {top: 100%}
  }
  @-keyframes floating{
    from {top: 0px}
    to {top: 1000px}
  }
  
  @-webkit-keyframes rotating{
    0% {transform: rotateZ(0deg) rotateX(0deg);}
    50% {transform: rotateZ(45deg) rotateX(180deg);}
    100% {transform: rotateZ(0deg) rotateX(360deg);}
  }