JSFiddle - React, Tailwind, and code Playground

HTML

<div style="padding-left:150px; ">
    <div style="float: left; width: 150px; margin-left:-150px; height: 200px; background-color: #eee">Navigation</div>
    <div style="float:left; background-color: #f00; width:100%;" >
        <div style="float: left; width: 50%; height: 100px; background-color: #ff0">Block</div>
        <div style="float: left; width: 50%; height: 20px; background-color: #f0f">Block</div>
        <div style="clear:both;"></div>
        <div style="float: left; width: 50%; height: 50px; background-color: #00f">This Block</div>
    </div>
</div>