JSFiddle - React, Tailwind, and code Playground

HTML

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

CSS

.circle 
{
    width: 200px;
    height: 200px;
    background: blue;
    -moz-border-radius: 100px;
    -webkit-border-radius: 100px;
    border-radius: 100px; 
}