JSFiddle - React, Tailwind, and code Playground

HTML

<div class="crystal"></div>

CSS

.crystal {
    width: 46px;
    height: 68px;
    top: -20px;
    position: relative;
    background-image: url("http://i.cubeupload.com/0GcJ1R.png");
    
    -webkit-animation: play 4s infinite;
       -moz-animation: play 4s infinite;
        -ms-animation: play 4s infinite;
         -o-animation: play 4s infinite;
            animation: play 4s infinite;
      animation-timing-function: linear;
}

@-webkit-keyframes play {
    0% { top: 0px; }
    50% { top: 30px; }
    100% { top: 0px; }
}

@-moz-keyframes play {
    0% { top: 0px; }
    50% { top: 30px; }
    100% { top: 0px; }
}

@-ms-keyframes play {
    0% { top: 0px; }
    50% { top: 30px; }
    100% { top: 0px; }
}

@-o-keyframes play {
    0% { top: 0px; }
    50% { top: 30px; }
    100% { top: 0px; }
}

@keyframes play {
    0% { top: 0px; }
    50% { top: 30px; }
    100% { top: 0px; }
}