.jblock {
 width: 40px; box-shadow: 4px 4px 10px #00000066; position: absolute; right: 0px; margin: 20px; bottom: 0px; cursor: pointer; opacity: 0.5;
}

.jblock:hover {
  opacity: 1;
 animation-name: bounce;
  animation-duration: 0.5s; 
}
@keyframes bounce {
  0%   {bottom:0px;animation-timing-function: ease-out;box-shadow: 4px 4px 10px #00000066;}
  25%  {bottom:10px;animation-timing-function: ease-in;box-shadow: 4px 14px 10px #00000066;}
  50% {bottom:0px;animation-timing-function: ease-out;box-shadow: 4px 4px 10px #00000066;}
  75%  {bottom:5px;animation-timing-function: ease-in;box-shadow: 4px 9px 10px #00000066;}
  100% {bottom:0px;animation-timing-function: ease-out;box-shadow: 4px 4px 10px #00000066;}
}