JSFiddle - React, Tailwind, and code Playground

HTML

<div id="outer">
    <div id="inner"></div>
</div>

CSS

#outer {
        position: relative;
        height: 100px;
        width: 10px; /* remove this to make it work */
    }
    #inner {
        position: absolute;
        bottom: 30%;
        background-color: #000;
        width: 10px;
        height: 10px;
    }

JavaScript

$( "#inner" ).animate({ bottom: "0%" });