JSFiddle - React, Tailwind, and code Playground

HTML

<div class='triangle' style="border-top-color: blue;"></div>

CSS

.triangle {
	border: solid transparent;
	content: ' ';
	height: 0;
    top: 0;
    left:0;
	position: absolute;
	width: 0;
	border-width: 12px;
}