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                <button id="button">Open Box</button>

<br />
<br />

<div id="box" class="box" style="display: none">
  <div class="inner">
    “If I find in myself a desire which no experience in this world can satisfy,
    the most probable explanation is that I was made for another world. If none
    of my earthly pleasures satisfy it, that does not prove that the universe is
    a fraud.” - C.S. Lewis



                .box {
  overflow: hidden;
  background: pink;
  color: red;
  width: 200px;
  transition: height 2s;

.inner {
  padding: 1rem;

:root {
    --blue: #4299e1;
    --darkblue: #2b6cb0;

div {
  text-align: center;

div span {
  margin: 0 auto;

* {
    font-size: 25px;
    font-family: 'Nunito', sans-serif;



                document.getElementById('button').addEventListener('click', () => {
  const box = document.querySelector('.box');

  // RESET : START = 'none'; = '';
  // RESET : END = '';

  // Measure the actual height.
  const height = `${box.clientHeight}px`; = '0px';

  requestAnimationFrame(() => {
    requestAnimationFrame(() => { = height;