JSFiddle - React, Tailwind, and code Playground

HTML

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

CSS

#parent
{
    position: relative;
    margin: 20px 20px;
    width: 200px;
    height: 200px;
    background: #ddd;
    box-shadow: 0px 2px 5px #555;
    border-radius: 5px;
}
#child
{
    top: 30px;
    left: 200px;
    position: absolute;
    width: 70px;
    height: 30px;
    background: rgba(0, 255, 0, 0.3);
    box-shadow: 1px 1px 3px #999;
    border-radius: 3px;
    text-align: right;
    z-index: -10;
}