JSFiddle - React, Tailwind, and code Playground

HTML

<div></div>

CSS

div{
    position: relative;
    height: 250px;
    width: 300px;
    background: green;
    margin: 0 auto;
}
div:before {
    position: absolute;
    z-index: -1;
    content: "";
    display: block;
    top: 7px; left: 0px;
    width: 100%;
    height: 100%;
    background: linear-gradient(to left, gray, lightgray 30%, lightgray 70%, gray 100%); 
    border-radius: 50%/10px;
    box-shadow: 0 2px 0 lightgray;
}