JSFiddle - React, Tailwind, and code Playground

HTML

<style>
#block {
        background: #fcc;
        height: 10px;
}
#inner {
        background: #ccf;
        height: 30px;
        width: 10px;
    float:left;
}
#after {
        background: #cfc;
        height: 10px;
    clear:both;
}
</style>
<div id="block">
        <div id="inner"></div>
</div>
<div id="after"></div>