JSFiddle - React, Tailwind, and code Playground

HTML

<div class="block"></div>

CSS

.block{
    position: relative;
    margin: 150px;
    width: 200px;
    height: 400px;
    color: #222;
    border: 1px solid #ccc;
    overflow: hidden;
}


.block:before{
    content:'';
    position: absolute;
    bottom:-5px;
    width: 100%;
    box-shadow: 3px 0 30px 5px #424242;
    border-radius: 20%;
}