JSFiddle - React, Tailwind, and code Playground

HTML

<div class="jsbar">This is dynamically created</div>
<div class="page">
    <header>The header bar</header>
   <div class="content">the content here
       <br /> 
    more content
    <br />
    and more content
    <br /></div>
</div>

CSS

.page {
    position:relative;
    top:0;
    padding-top:40px;
    background:#f8f8f8;
    height:900px;
}
header {
    position:fixed;
    top:20px;
    background:#eee;
    height:20px;
}
.jsbar {
    position:fixed;
    top:0;
    background:#ccc;
    height:20px;
    z-index:30000;
}