JSFiddle - React, Tailwind, and code Playground

HTML

<div class="shape"></div>

CSS

.shape { 
    width: 200px; 
    height: 50px; 
    background: #000;
    margin: 50px;
    position: relative;
}

.shape:before {
    display: block;
    content: "";
    height: 0;
    width: 0;
    border: 25px solid #000;
    border-bottom: 25px solid transparent;
    border-left: 25px solid transparent;
    position: absolute;
    left: -50px;
}

.shape:after {
    display: block;
    content: "";
    height: 0;
    width: 0;
    border: 25px solid #000;
    border-top: 25px solid transparent;
    border-right: 25px solid transparent;
    position: absolute;
    right: -50px;
}