JSFiddle - React, Tailwind, and code Playground

HTML

<div id="bigwindow" style="height:3000px; width:100%;background:lightgrey;"><div style="margin-top:500px;">I'm a normally scrolling element.</div></div>
<div id="downparallax" style="position:fixed;bottom:0;background:white;">Hello world!<br/>I move in parallax!</div>
<div id="rightparallax" style="position:fixed;left:0;top:50%;background:white;border:1px solid black">I move right when you scroll down!</div>

JavaScript

window.onscroll = function() {
    document.getElementById("downparallax").style.bottom = window.scrollY/2.0+"px";
    document.getElementById("rightparallax").style.left = window.scrollY+"px";
}