JSFiddle - React, Tailwind, and code Playground

HTML

<div></div>

CSS

div:before{  
    content: "";
   width: 0;
   height: 0;
   position: relative;
   top: 15px;
   border-style: solid;
   border-width: 12px 12px 0 12px;
   border-color: #000 transparent transparent transparent;
   -webkit-transform: rotate(270deg); 
    -webkit-transform-origin: 50% 50%;
    -webkit-box-shadow: 0 1px 2px rgba(0,0,0,0.1);
    box-shadow: 0 1px 2px #000;
}