JSFiddle - React, Tailwind, and code Playground

HTML

<div class="main">
    <div class="inner">
        <div>123</div>
        <div>456</div>
    </div>
    <div>999</div>
</div>

CSS

div.main
{
    width: 300px;
    border: 2px solid #98999E;
    overflow: auto;
}

div.main > div
{
    float: right;
    border: 2px solid #FF3700; 
    margin: 2px;
}

div.inner > div
{
     float: right;
}