JSFiddle - React, Tailwind, and code Playground

HTML

<div class="content">
    Loriem ispsum is simpaly dummy text<br>
    Loriem ispsum is simpaly dummy text<br>
    Loriem ispsum is simpaly dummy text<br>
    Loriem ispsum is simpaly dummy text<br>
    Loriem ispsum is simpaly dummy text<br>
    Loriem ispsum is simpaly dummy text<br>
    Loriem ispsum is simpaly dummy text<br>
    Loriem ispsum is simpaly dummy text<br>
    Loriem ispsum is simpaly dummy text<br>
    Loriem ispsum is simpaly dummy text<br>
    Loriem ispsum is simpaly dummy text<br>
    Loriem ispsum is simpaly dummy text<br>
    Loriem ispsum is simpaly dummy text<br>
    

  <div class="gradientback">

  </div>
</div>

CSS

body{background:#000;}
.content{
    width:500px;
    height:300px;
    position:relative;
    color:#fff;
    overflow:hidden;
}
.gradientback{
    
    position:absolute;
    bottom:0px;
    left:0px;
    width:100%;
    height:50px;
    background: -webkit-linear-gradient(top,  rgba(137,255,241,0) 0%,rgba(0,0,0,1) 100%); /* Chrome10+,Safari5.1+ */
}

JavaScript

$("#mainNavigation > div > ul > li").each(function() {
    $(this).html("<div class=\"relContainer\">"+$(this).html()+"</div>");
    var w = parseInt($(this).css('width'));
    //$(this).css('width', w +"px");
    
    
    var a = $(this).find(".relContainer > a");
    a.css('width', (w-5) + "px");
    
    if($(this).find(".inner").length) {
        $('<div class="placeHolder" style="width: '+ $(this).find(".relContainer > a").innerWidth() +'px;"></div>').insertAfter($(this).find(".relContainer > a"));
    }
});