mystyle.css

#btn-download {
  cursor: pointer;
  display: block;
  width: 2.25em;
  height: 2.25em;
  border-radius: 50%;
  -webkit-tap-highlight-color: transparent;
  position: absolute;
  bottom: 0.8em;
  right: 0.8em;
  background: rgba(166, 168, 172, 0.5);
}
#btn-download:hover {
  background: rgba(255, 255, 255, 1);
}
#btn-download svg {
  margin: 0.28em 0 0 0.48em;
  fill: none;
  transform: translate3d(0, 0, 0);
}
#btn-download svg polyline,
#btn-download svg path {
  stroke: rgb(38, 38, 38);
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
  transition: all 0.3s ease;
  transition-delay: 0.3s;
}
#btn-download svg path#check {
  stroke-dasharray: 38;
  stroke-dashoffset: 114;
  transition: all 0.4s ease;
}
#btn-download.downloaded {
  background: rgba(255, 255, 255, 1);
}
#btn-download.downloaded svg .svg-out {
  opacity: 0;
  animation: drop 0.3s linear;
  transition-delay: 0.4s;
}
#btn-download.downloaded svg path#check {
  stroke: rgb(237, 73, 86);
  stroke-dashoffset: 174;
  transition-delay: 0.4s;
}

@keyframes drop {
  20% {
    transform: translate(0, -3px);
  }
  80% {
    transform: translate(0, 2px);
  }
  95% {
    transform: translate(0, 0);
  }
}