JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
    <div id="header">Header</div>
    <div id="content">
        <div id="inner_header">Inner Header</div>
        <div id="scrollable_content">Very long content 1
            <br />Very long content 2
            <br />Very long content 3
            <br />Very long content 4
            <br />Very long content 5
            <br />Very long content 6
            <br />Very long content 7
            <br />Very long content 8
            <br />Very long content 9
            <br />Very long content 2
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long content
            <br />Very long...

CSS

html, body {
    height:100%;
    margin: 0;
    padding: 0;
    overflow: hidden;
}
div {
    margin: 0;
    padding: 0;
    /*border: 1px solid black;*/
}
div#content {
    height: 100%;
}
div#header, div#inner_header {
    height: 25px;
    background-color: gray;
    color: white;
}
div#container {
    height:100%;
}
div#scrollable_content {
    position: absolute;
    top: 50px;
    bottom: 0px;
    overflow-y:auto;
    border: 1px solid green;
    width: 100%;
}