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                <div class="container">
	<div class="bubble"></div>
	<div class="bubble"></div>
	<div class="bubble"></div>
	<div class="bubble"></div>
	<div class="bubble"></div>

	<p class="intructions">Move the cursor / touch around to bring some color!</p>


                /* breath behaves based on the
CSS variables values that are inherited */
@keyframes breath {
	0% {
		background: var(--colorStart);
		transform: scale(var(--scaleStart));
	100% {
		background: var(--colorEnd);
		transform: scale(var(--scaleEnd));

.container {
	background: black;
	/* all "breath" animations inside */
	/* will start grey... */
	--colorStart: #222;
	/* and end white'ish (until you start to move the cursor around) */
	--colorEnd: #eee;
	color: var(--colorEnd);

.bubble {
	/* each bubble starts with these common specs: */
	--scaleStart: 0.3;
	background: var(--colorStart);
	transform: scale(var(--scaleStart));
	animation: breath 2s alternate infinite ease-in-out;

/* customize each bubble specs... */

.bubble:nth-child(5) {
	--scaleEnd: 1;

.bubble:nth-child(4) {
	--scaleEnd: 1.2;
	animation-delay: -250ms;

.bubble:nth-child(3) {
	--scaleEnd: 1.6;
	animation-delay: -500ms;

/* styles not related to the animation */

.container {
	display: flex;
	align-items: center;
	justify-content: center;
	min-height: 100vh;
	max-width: 100vw;

.bubble {
	margin: 1rem;
	width: 2.5rem;
	height: 2.5rem;
	border-radius: 50%;

.intructions {
	position: absolute;
	width: 100%;
	top: 0; left: 0;
	padding-top: 2rem;
	font-family: sans-serif;
	font-weight: 600;
	text-align: center;



                /* Bonus: Use JS to improve even more CSS @keyframes
Here we just use it to update the color */

const doc = document.documentElement;
const container = document.getElementsByClassName('container')[0];

doc.addEventListener("touchmove", updateBubbleColors);
doc.addEventListener("mousemove", updateBubbleColors);

function updateBubbleColors(e) {
  const w = window.innerWidth / 255;
  const h = window.innerHeight / 255;
  const x = parseInt(e.pageX / w, 10);
  const y = parseInt(e.pageY / h, 10);

  const r = x;
  const g = (y - 255) * -1;
  const b = x <= y ? y - x : 0;'--colorEnd', `rgb(${r},${g},${b})`);