JSFiddle - React, Tailwind, and code Playground

HTML

<div id="topbar">
    hello
</div>
<div id="sidebar">
    <div id="title">
        title
    </div>
    <div id="main">
        blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah 
    </div>
</div>

CSS

#topbar {
    height: 40px;
    background-color: blue;
}

#sidebar {
position: absolute;
top: 40px;
bottom: 0px;
width: 80px;
overflow: hidden;   
}

#title {
    height:30px;
    background-color: red;
}

#main {
    height: auto;
    overflow: scroll;
}