JSFiddle - React, Tailwind, and code Playground

HTML

<div id="left"></div>
<div id="main">
     <h1>test</h1>

</div>

CSS

#left {
    float:left;
    width:200px;
    height:400px;
    background:#cfc;
}
#main {
    margin-left:210px;
    background:#f9c;
    height:400px;
    overflow:auto;
}
h1 {
    clear:both;
}