JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
    <div id="inside">
        Fixed your problem.
    </div>
</div>

CSS

#container {
    width:90%;
    height:400px;
    overflow:scroll;
    border:1px solid blue;
   
}

#inside {
    width:90%;
    height:100%;
    margin-left:auto;
    margin-right:auto;
    border:1px solid red;
}