JSFiddle - React, Tailwind, and code Playground

HTML

<div id="parent">
    <div id="childWrap">
        <div id="child"> sdfasdfasdf </div>
    </div>
</div>

<div style="clear: both; padding: 20px 0px 20px 0px;">
Red = background of #parent
<br /><br />
Green = background of #childWrap 
<br /><br />
yellow = background of #child
</div>


<div id="parent">
    <div id="childWrap">
        <div id="child" class="size"> sdfasdfasdf </div>
    </div>
</div>

CSS

#parent { background: red; float: left; padding: 3px; }
#childWrap { background: green; float: left; }
#child { background: yellow; float: left; margin: 10px; padding: 10px; }

.size { width: 400px; height: 300px;}