JSFiddle - React, Tailwind, and code Playground

HTML

<div id="arrow">
</div>
<div id="box">
</div>

CSS

#arrow{
	border-left: 15px dashed transparent;
	border-right: 15px dashed transparent;
	
	border-bottom: 15px dashed grey;
    margin-left:200px;
    width:0;
    height:0;
}
#box{
    background:grey;
    width:300px;
    height:300px;
}