JSFiddle - React, Tailwind, and code Playground

HTML

<div style="width:800px;height:40px;position:absolute;border:1px solid black;">
		<div style="margin-right:-4px;padding:0;background:red;height:40px;display:inline-block">something</div>
		<div style="margin-right:-4px;padding:0;background:green;height:40px;display:inline-block">something</div>
		<div style="margin-right:-4px;padding:0;background:blue;height:40px;display:inline-block">something</div>
	</div>

JavaScript

$(document).ready(function(){
	$('div div').width($('div:first-child').width() / 3);
});