JSFiddle - React, Tailwind, and code Playground

HTML

<div id="wrap">
    <nav id="main-menu">
        <ul>
            <li><a class="first-link parent" rel="first-widget" href="">First Link</a></li>
            <li><a class="second-link parent" rel="second-widget" href="">Second Link</a></li>
            <li><a class="third-link parent" rel="third-widget" href="">Third Link</a></li>
            <li><a class="fourth-link parent" rel="fourth-widget" href="">Fourth Link</a></li>
        </ul>
    </nav><!-- #main-menu !-->

    <div id="first-widget" class="widget-container">
                <h2>Sub Title 1</h2>              
                <p>Lorem Ipsum
                <a href="#">Read More</a></p>
     </div><!-- .first-widget !-->
    <div id="second-widget" class="widget-container">
                <h2>Sub Title 2</h2>              
                <p>Lorem Ipsum
                <a href="http://www.facebook.com">Read More</a></p>
                <ul>
                <li>Hey1 h</li>
                </ul>
    </div><!-- .second-widget !-->
    <div id="third-widget" class="widget-container">
                <h2>Sub Title 3</h2>              
                <p>Lorem Ipsum
                <a href="#">Read More</a></p>
    </div><!-- .third-widget !-->
    <div id="fourth-widget" class="widget-container">
                <h2>Sub Title 4</h2>              
                <p>Lorem Ipsum
                <a href="#">Read More</a></p>
    </div><!-- .fourth-widget !-->
</div>

CSS

#wrap {
    position: relative;
    top: 10px;
    left: 10px;
    border: 1px solid black;
}
#main-menu li {
    display: inline;
}
.widget-container {
    display: none;
}

JavaScript

$('#main-menu a').mouseover(function() {
   var $this = $(this);
   var id = $this.attr('rel');
   var $currentWidget = $('#' + id);
   $currentWidget.show().siblings('.widget-container').hide();
});
$('#wrap').mouseleave(function() {
    $('.widget-container').hide();
});