JSFiddle - React, Tailwind, and code Playground

HTML

<div class="arrow-up"></div>

CSS

.arrow-up:after {
        position:absolute;
        content:"";
        width: 0;
        height: 0;
        margin-top:1px;
        margin-left:2px;
        border-left: 10px solid transparent;
        border-right: 10px solid transparent;
        border-bottom: 10px solid white;
    }
    
    .arrow-up:before {
        position:absolute;
        content:"";
        width: 0;
        height: 0;
        border-left: 12px solid transparent;
        border-right: 12px solid transparent;
        border-bottom: 12px solid black;
    }