JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="//code.jquery.com/ui/1.11.4/themes/smoothness/jquery-ui.css">
<script src="//code.jquery.com/jquery-1.11.3.js"></script>
<script src="//code.jquery.com/ui/1.11.4/jquery-ui.js"></script>
<p>(In FIREFOX only) The active feature is ignored- li won't turn green when clicking (Yes- It works in IE & Chrome)</p>
<p>If we comment out both JS lines- it will work in firefox- The li will turn green once clicking with the mouse.</p>
<p>Those two jquery lines break firefox's css active functionality</p>
<ul id="sortable">
  <li class="ui-state-default"><span class="ui-icon ui-icon-arrowthick-2-n-s"></span>Item 1</li>
  <li class="ui-state-default"><span class="ui-icon ui-icon-arrowthick-2-n-s"></span>Item 2</li>
  <li class="ui-state-default"><span class="ui-icon ui-icon-arrowthick-2-n-s"></span>Item 3</li>
  <li class="ui-state-default"><span class="ui-icon ui-icon-arrowthick-2-n-s"></span>Item 4</li>
</ul>

CSS

body {	font-family: "Trebuchet MS", "Helvetica", "Arial",  "Verdana", "sans-serif";	font-size: 62.5%;}
p{font-size: 18px;}
#sortable {    list-style-type: none; margin: 0; padding: 0; width: 60%;}
#sortable li {     margin: 0 3px 3px 3px; padding: 0.4em; padding-left: 1.5em; font-size: 1.4em; height: 18px;}
#sortable li span {     position: absolute; margin-left: -1.3em;}

li:active{
    background: green;
    cursor: n-resize; 
}

JavaScript

$(function() {
    //Notice that if we comment both lines (not one), Firefox acive css will work again.
    $( "#sortable" ).sortable();
    $( "#sortable" ).disableSelection();
  });