JSFiddle - React, Tailwind, and code Playground

HTML

<div id="mobile">I am the mobile website!</div>
<div id="desktop">I am the desktop website! Rawr!</div>

JavaScript

$(document).ready(function(){resize();});
$(window).resize(function(){resize();});

function resize()
{
    var mobileMaxWidth = 640; //Define this to whatever size you want
    if($(window).width() > mobileMaxWidth)
    {
        $("div#desktop").show();
        $("div#mobile").hide();
    }
    else
    {
        $("div#desktop").hide();
        $("div#mobile").show();
    }
}