JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
        <div id="content">
            <div id="leftnav">left nav</div>
            <div id="rightnav">right nav</div>
        </div>
</div>

CSS

#content {
        width: 700px;
        margin:20px auto 0;
    }

    #leftnav {
        float: left;
        width: 200px;
        border:1px solid #000;
    }

    #rightnav {
        width: 200px;
        float: left;
        border:1px solid #000;
    }