JSFiddle - React, Tailwind, and code Playground

HTML

<div id="fixed"></div>

CSS

body {
    height:1500px;
}
#fixed {
    width:218px;
    height:57px;
    background:red;
    position:fixed;
    bottom:0;
    margin-left:200px;
}

JavaScript

$(document).ready(function () {
    var offset = $("#fixed").offset();

    $(window).scroll(function () {
        if ($(window).scrollTop() > offset.top) {
            $("#fixed").css({
                'bottom': '0px',
                    'position': 'fixed'
            });
        } else {
            $("#fixed").css({
                'bottom': '120px',
                    'position': 'fixed'
            });
        }
    });

});