JSFiddle - React, Tailwind, and code Playground

HTML

<div id="head"> i </div>
<div id="subHead"> can </div>
<div id="content">  haz </div>

CSS

#head, #subHead{
    position: fixed;           
    height: 80px;    
    width: 100%;
    display: block;
    background: #c00;
    left: 0;
    top: 0;
    z-index: 10;
}

#subHead{
    z-index: 4;
    background: #cd0; 
    top: 80px;
}

#content{
    position: relative;
    z-index: 6;
    height: 1000px;
    background: #eee;
    margin-top: 160px;
}

JavaScript

window.onscroll = function(ev){
  var subHead = document.getElementById('subHead'),
      topHeight = document.getElementById('head').offsetHeight,
      scrollTop = document.documentElement.scrollTop || document.body.scrollTop;

  subHead.style.top = (topHeight - scrollTop / 4) + 'px';
};