JSFiddle - React, Tailwind, and code Playground
HTML
<div id="grayinnerbackground">
</div>
CSS
div#grayinnerbackground {
margin: auto;
width: 50px;
background-color: #D9D9D9;
height: 100%;
position: fixed;
z-index: -1;
}
<div id="grayinnerbackground">
</div>
div#grayinnerbackground {
margin: auto;
width: 50px;
background-color: #D9D9D9;
height: 100%;
position: fixed;
z-index: -1;
}