JSFiddle - React, Tailwind, and code Playground

HTML

<div id="foo">
    <div id="bar">
    </div>
</div>

CSS

/**
 * Double Opacity
 */
body{background:;}

#foo{
    height:150px;
    width:250px;
    background:rgba(0, 0, 0, 0.6);
    position:absolute;
    left:40%;
    top:20%;
}

#bar{
    height:40px;
    width:40px;
    background:#030;
    border-radius:40px;
    position:absolute;
    top:-15px;
    left:-15px;
}