JSFiddle - React, Tailwind, and code Playground

HTML

<div id="sidebar"></div>
<div id="content"></div>

CSS

#sidebar{
    width: 40px;
    height:350px;
    float: left;
    margin-left: 10px;
    border: 1px solid red;
}

#content{
    width: 165px;
height:350px;
    float: left;
    margin-left: 10px;
    border: 1px solid blue;
}