JSFiddle - React, Tailwind, and code Playground

HTML

<div id='wrapper'>
  <div id="boxadoo">
<ul>
<li>Box 1</li>
<li>Box Two</li>
<li>Tres Box</li>
<li>Box Box Box Box</li>
<li>Box (Box * 5)</li>
<li>Boxcar Racer</li>
    </ul>
  </div>
</div>

CSS

#wrapper {
    position:absolute;
    background-color: #ccc;
    width: auto;
    min-width: 100%;
    background-color: #FFFFFF;
    top:44px;
    left: 0;
    right: 0;
    height: 48px;
    line-height: 46px;
    overflow-x: hidden;
    z-index:100001;
    color: #CCC;
    font-family: "Helvetica Neue Bold", Helvetica;
}
#boxadoo {
    width: auto;
    overflow: hidden;
}
#boxadoo ul {
    background-color: #eee;
    font-size: 1em;
    color: black;
    position: relative;
    left: 0;
    width: auto;
    margin: 0;
    padding: 0;
}
#boxadoo li {
    background-color: pink;
    display: inline-block;
    margin: 0;
    padding: 0 10px 0 0;
}

JavaScript

var elem = $('#boxadoo').find('ul'),
width = 0;

console.log(">> Setting dynamic width: " + width);
elem.find('li').each(function(){
        console.log(width + ' += ' + $(this).outerWidth());
        width += $(this).outerWidth();
    })
console.log("Final width: "+width);
elem.css('width', width);