JSFiddle - React, Tailwind, and code Playground

HTML

<div>first</div>
<div>second</div>
<div>third</div>

CSS

.tagging{
   border: 1px solid black;
   width : 20px;
   height: 30px;

}

JavaScript

var div = document.getElementsByTagName("div");
div[0].className = "tagging";