JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    <div style="background-color: red; height: 400px; width: 200px;"></div>
    <div style="background-color: green; height: 400px; width: 200px;"></div>
    </div>
    <br /><br /><br /><br /><br /><br />
    <div style="height: 100%; width: 100%;" class="siteWrapper">
    <div style="background-color: red; height: 400px; width: 200px; float: left;"></div>
    <div style="background-color: green; height: 400px; width: 200px; margin-left: 201px;"></div>
    </div>
    <br /><br /><br /><br /><br /><br />
    <div class="wrap">
    <div style="background-color: red; height: 400px; width: 200px;"></div>
    <div style="background-color: green; height: 400px; width: 200px;"></div>
    </div>
    <br /><br /><br /><br /><br /><br />
    <div class="no-clearfix wrap">
    <div style="background-color: red; height: 400px; width: 200px;"></div>
    <div style="background-color: green; height: 400px; width: 200px;"></div>
    </div>
    <br /><br /><br /><br /><br /><br />
    <div class="clearfix wrap">
    <div style="background-color: red; height: 400px; width: 200px;"></div>
    <div style="background-color: green; height: 400px; width: 200px;"></div>
    </div>

CSS

.clearfix:before, .clearfix:after {
    content: "\0020";
    display: block;
    height: 0;
    overflow: hidden;
    }
    .clearfix:after {
    clear: both;
    }
    .no-clearfix {
    clear: both;
    }
    .wrap {
    padding: 20px;
    background-color: #bad;
    }
    .wrap img {
    float: left;
    }
    br {
    clear: both;
    }