JSFiddle - React, Tailwind, and code Playground

HTML

<div class="wrap">
    <div class="inner"></div>
</div>

CSS

.wrap {
    background: #CC0001;
    height: 200px;
    width: 600px;
}

.wrap .inner {
    height: 200px;
    width: 200px;
    background: #fff;
    border-radius: 0 50% 50% 0;
}