JSFiddle - React, Tailwind, and code Playground

HTML

<div class='outer'>
    <div class='inner'>
        Inner.
    </div>
    Outer.
</div>

CSS

div.outer {
    position: absolute;
    left: 10px;
    top: 10px;
    border: 5px solid green;
    padding: 10px;
}
div.inner {
    position: absolute;
    left: 0;
    top: 100%;
    border: 10px solid red;
    padding: 15px;
}