JSFiddle - React, Tailwind, and code Playground

HTML

<div></div>

CSS

div {
    width:200px;
    background:red;
    height:100px;
    -webkit-border-bottom-right-radius: 100px 50px;
    -webkit-border-bottom-left-radius: 100px 50px;
    -moz-border-radius-bottomright: 100px 50px;
    -moz-border-radius-bottomleft: 100px 50px;
    border-bottom-right-radius: 100px 50px;
    border-bottom-left-radius: 100px 50px;
}