JSFiddle - React, Tailwind, and code Playground

HTML

<div id="menu2">Nav</div>

CSS

#menu2 {
    background-color: green;
}

#menu2.f-nav {
    background-color: red;
}

JavaScript

function checkWidth() {
    if ($(window).width() < 514) {
        $('#menu2').addClass('f-nav');
    } else {
        $('#menu2').removeClass('f-nav');
    }
}

$(window).resize(checkWidth);