JSFiddle - React, Tailwind, and code Playground

HTML

<div class="">
<div>
<div class="sub">first child</div>
</div>
    <div class="sub">
    <div class="sub">first child</div>
    </div>
    
</div>
<div class="bfc">
    <div class="sub">second child</div>
</div>

CSS

.bfc { overflow:hidden; zoom:1; }
.sub { margin:10px 0; background:#ccc; }
.float{float:left}