JSFiddle - React, Tailwind, and code Playground

HTML

<div style="
            /*border-top-left-radius: 100%;*/
            -moz-border-radius-bottomleft: 100%;
            box-shadow: rgb(255, 0, 0) 0px 0px 0px 20px inset;
            background-color: #ccc;
            width: 200px;
            height: 100px;
              display:block;
            border:1px solid transparent;
"></div>

CSS

html, body {
    height: 100%;
}