JSFiddle - React, Tailwind, and code Playground

HTML

<div class="back">
</div>

CSS

.back {
    background-color:red;
    /* for Chrome */
    -webkit-border-top-left-radius: 40px;
    -webkit-border-top-right-radius: 10px;
    -webkit-border-bottom-right-radius: 80px;
    -webkit-border-bottom-left-radius: 20px;
 
    /* for Firefox */
    -moz-border-radius-topleft: 40px;
    -moz-border-radius-topright: 10px;
    -moz-border-radius-bottomright: 80px;
    -moz-border-radius-bottomleft: 20px;
}