JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
    <li><span class="close">1</span></li>
    <li><span class="open">2</span></li>
    <li><span class="close">3</span></li>
    <li><span class="close">4</span></li>
    <li><span class="open">5</span></li>
    <li><span class="close">6</span></li>
    <li><span class="close">7</span></li>
</ul>

JavaScript

var last_open_li = $('.open').last().parent();
var last_close_li = $('.close').last().parent();

last_open_li.css({background: 'green'});
last_close_li.css({background: 'red'});