<link href="https://fonts.googleapis.com/css?family=Varela+Round" rel="stylesheet">

<div class="panels">
  <div class="panel panel1">
    <p>Hey</p>
    <p>Let's</p>
    <p>Dance</p>
  </div>
  <div class="panel panel2">
    <p>Give</p>
    <p>Take</p>
    <p>Receive</p>
  </div>
  <div class="panel panel3">
    <p>Experience</p>
    <p>It</p>
    <p>Today</p>
  </div>
  <div class="panel panel4">
    <p>Give</p>
    <p>All</p>
    <p>You can</p>
  </div>
  <div class="panel panel5">
    <p>Life</p>
    <p>In</p>
    <p>Motion</p>
  </div>
</div>

html {
  box-sizing: border-box;
  background: #ffc600;
  font-family: 'Varela Round', sans-serif;
  font-size: 20px;
  font-weight: 400;
}

body {
  margin: 0;
}

*,
*:before,
*:after {
  box-sizing: inherit;
}

.panels {
  min-height: 100vh;
  overflow: hidden;
  display: flex;
}

.panel {
  background: #6b0f9c;
  color: #000;
  text-align: center;
  align-items: center;
 
  transition:
    font-size 0.7s cubic-bezier(0.61,-0.19, 0.7,-0.11),
    flex 0.7s cubic-bezier(0.61,-0.19, 0.7,-0.11),
    background 0.2s;
  font-size: 20px;
  background-size: cover;
  background-position: center;
  flex: 1;
  justify-content: center;
  display: flex;
  flex-direction: column;
}

.panel1 {
  background: #ebd777;
}

.panel2 {
  background: #aece82;
}

.panel3 {
  background: #75c489;
}

.panel4 {
  background: #42bb92;
}

.panel5 {
  background: #12b79c;
}

.panel > * {
  margin: 0;
  width: 100%;
  transition: transform 0.5s;
  flex: 1 0 auto;
  display: flex;
  justify-content: center;
  align-items: center;
}

.panel > *:first-child {
  transform: translateY(-100%);
}

.panel.open-active > *:first-child {
  transform: translateY(0);
}

.panel > *:last-child {
  transform: translateY(100%);
}

.panel.open-active > *:last-child {
  transform: translateY(0);
}

.panel p {
  font-size: 0.8em;
  opacity: 0.3;
}

.panel p:nth-child(2) {
  font-size: 2.5em;
}

.panel.open {
  flex: 5;
  font-size: 40px;
}

const panels = document.querySelectorAll('.panel');

function toggleOpen() {
  this.classList.toggle('open');
}

function toggleActive(e) {
  console.log(e.propertyName);
  if(e.propertyName.includes('flex')) {
   this.classList.toggle('open-active'); 
 }
}

panels.forEach(panel => panel.addEventListener('click', toggleOpen));
panels.forEach(panel => panel.addEventListener('transitionend', toggleActive));