JSFiddle - React, Tailwind, and code Playground

HTML

<div>&nbsp;<a>o<a>o</a><hr>

CSS

a,div{width:2em;border:2px solid;border-radius:50%}

JavaScript

window.setInterval(function(){
    if ($("hr").length>1) $("hr:first").remove(); else $("hr").after("<hr>");},500);