JSFiddle - React, Tailwind, and code Playground

by Alex Coleman

HTML

<div class="box"></div>

CSS

.box {
	position: relative;
    border: 1px solid #000;
    height:100px;
    width:300px;
    margin-top:100px;
    background:#fff;
}
.box:after, .box:before {
	bottom: 100%;
	left: 50%;
	border: solid transparent;
	content: " ";
	height: 0;
	width: 0;
	position: absolute;
	pointer-events: none;
}

.box:after {
	border-color: rgba(136, 183, 213, 0);
	border-bottom-color: #fff;
	border-width: 30px;
	margin-left: -30px;
}
.box:before {
	border-color: rgba(194, 225, 245, 0);
	border-bottom-color: #000;
	border-width: 31px;
	margin-left: -31px;
}