JSFiddle - React, Tailwind, and code Playground

HTML

<!doctype html>
<html lang="en">
    <head>
        <style type="text/css">
        
            * {
                margin: 0;
                padding: 0;
                border: 0;
            }
            div.container {
                position: absolute;
                top: 100px;
                left: 100px;
                right: 100px;
                bottom: 100px;
                overflow: auto;
                padding: 20px;
                border: #000 1px solid;
            }
        
        </style>
    </head>
    <body class="default">
    
        <div class="container">
        
            <div style="height:800px;background:red;"></div>
        
            <div>This is some text...</div>
        
        </div>
    
    </body>
</html>

CSS

div.container:after{
        content:"";
        display:block;
        height:20px; /* Which is the padding of div.container */
    }