JSFiddle - React, Tailwind, and code Playground

HTML

<html>
    <head>
    <style type="text/css">
        * { margin:0; padding:0; }
        .parent { clear:both; margin:auto; width:1060px; }
        .child1 { background-color:#999999; width:260px; display:table-cell}
        .child2 { background-color:#99CC00; width:800px;display:table-cell }
        .child1a, child2a { float:left; width:100%; }
        .child2a { border-bottom:1px solid #000000; height:500px; }
    </style>
    </head>

    <body>
    <div class="parent">
        <div class="child1">
            <div class="child1a">1</div>
            <div class="child1a">2</div>
            <div class="child1a">3</div>
        </div>
        <div class="child2">
            <div class="child2a">1</div>
            <div class="child2a">2</div>
            <div class="child2a">3</div>
        </div>
    </div>
    </body>
</html>