JSFiddle - React, Tailwind, and code Playground

HTML

<div class="circle">test</div>

CSS

.circle {
    display: block;
    height: 100px;
    width: 100px;
    border-radius: 55px;
    text-align: center;
    font-size: 12px;
    background-color: red;
    bottom: 100px;
    left: 10px;
    position: fixed;
}

JavaScript

$('.circle').on('click', function() {
    alert('hello');
});