JSFiddle - React, Tailwind, and code Playground

HTML

<div id="menu">
    <ul>
       <li class="section-title">HEADER which triggers dropdown</li>
       <li><a href="#">element one</a></li>
       <li><a href="/_display/light/">element one</a></li>
       <li><a href="#">element one</a></li>
    </ul>
    <ul>
       <li class="section-title">HEADER #2 which triggers dropdown</li>
       <li><a href="#">element one</a></li>
       <li><a href="someotherplace/light/">element one</a></li>
       <li><a href="#">element one</a></li>
    </ul>
</div>

CSS

a{color:red;}
.activelink{background-color:yellow}

JavaScript

var loc = window.location;

$('#menu li a').each(function(){
    if (this.href == loc)
        $(this).addClass('activelink');
});

$('#menu ul:not(:has(.activelink)) li:not(:first-child)').hide();