JSFiddle - React, Tailwind, and code Playground

HTML

<div style="display:-webkit-flex;height:100%">
    <div style="background:#f00;width:50px">
    </div>
    <div style="display:-webkit-flex;-webkit-align-items:center;-webkit-justify-content:center;background:#0f0;-webkit-flex:1;overflow-Y:scroll">
        <div style="background:#000;width:10px;height:300px">
            HELLO
        </div>
    </div>
    <div style="background:#f00;width:50px">
    </div>
</div>

CSS

html, body
{
    background: #000;
    width: 100%;
    height: 100%;
    margin: 0;
}