JSFiddle - React, Tailwind, and code Playground

HTML

<div>
</div>

CSS

div {
    width: 310px;
    height: 41px;
    background: gray;
    border-radius: 5px;
    position: relative;
}
div:after {
    content: '';
    display: block;
    width: 30px;
    height: 60px;
    background: white;
    border-radius: 50%;
    position: absolute;
    right: -30px;
    bottom: -30px;
}