JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/themes/dot-luv/jquery-ui.css">
<div id="footer"><a href="#">Test Link</a></div>

CSS

#footer a { border-bottom: solid 1px transparent; }

JavaScript

$(document).ready(function(){
    $('#footer a').mouseover(function(){
    $(this).animate({
        borderBottomColor: '#D8D8D8'
        }, 1000, function() {
        // Animation complete.
    });
    });
});