JSFiddle - React, Tailwind, and code Playground

HTML

<div class="moving-article">

    <div class="container">

    <header class="fixed-header">FIXED HEADER</header>
       
        <ul>
        <li>SCROLL</li>
        <li>SCROLL</li>
        <li>SCROLL</li>
        </ul>    
    
    </div>

</div>

CSS

.moving-article {
    height: 150px;
    width: 75%;
    overflow-x: scroll;
 
}

.fixed-header {
    background: rgba(0,0,0,0.5);
    width: 50%;
    text-align: center;
    line-height: 40px;
    position: absolute;
    top: 0;
    left: 0;
}

.container{
    width: 1000px;
}

/* IGNORE BELOW CSS - JUST FOR PRESENTATION */

* { 
    margin: 0;
    padding: 0;
}
body {
    font-family: 'arial', cursive;
    color: #fff;
 }

.unmoving-article {
  -webkit-font-smoothing: subpixel-antialiased; /* avoid font get thinner */
  border: solid 10px #fff;
  height: 150px;
  overflow: scroll;
  position: relative;
  width:50%;
}

li { 
  background: #7081FF;
  min-height: 100px;
  text-align: center;
  vertical-align: middle;
  display: -webkit-flex;
  -webkit-align-items: center;
  -webkit-justify-content: center;
  } 
li:nth-of-type(2) {
  background: #434d99;  
}

JavaScript

var leftOffset = parseInt($(".fixed-header").css('left'));
$(window).scroll(function(){
    $('.fixed-header').css({
        'left': $(this).scrollLeft() + leftOffset
    });
});