JSFiddle - React, Tailwind, and code Playground

CSS

@keyframes leaf
{
    from 
    {
        opacity:0;
    }
    to
    {
        opacity:1;
    }
}
div:hover 
    {
    border:1px solid black;
    -webkit-animation-name:leaf;
    -webkit-animation-duration: 2s;
    -webkit-animation-timing-function: linear;
    -webkit-animation-iteration-count: infinite;
    -webkit-animation-delay: 1s;
    }
div {
    
    background-color: blue; width: 300px; height: 300px;
    border-top-right-radius:170px;
    border-bottom-left-radius:170px;
    }

JavaScript

$('<div>').appendTo(document.body).animate({opacity:0}, 700);