<button id="slowmo">Slow motion <span>mode</span></button>

<div class="device">
  <div class="container">
    <button id="burger" class="open-main-nav">
      <span class="burger"></span>
      <span class="burger-text">Menu</span>
    </button>
    <nav class="main-nav" id="main-nav">
      <ul>
        <li>
          <a href="#">About me</a>
        </li>
        <li>
          <a href="#">Speaker &amp; Writer</a>
        </li>
        <li>
          <a href="#">Work</a>
        </li>
        <li>
          <a href="#">Contact</a>
        </li>
        <li>
          <a href="#">Blog</a>
        </li>
      </ul>
    </nav>
    <p class="notice">Design Copyright <strong>Stéphanie Walter</strong><br><a href="https://stephaniewalter.design/" target="_blank">StephanieWalter.Design</a></p>
  </div>
</div>

/* Main menu positionning */
.main-nav {
    position: absolute;
    top: 0;
    right: 0;
    left: 0;
    bottom: 0;
    text-align: center;
    background: #FFF;
    opacity: 0;
    z-index: -1;
    visibility: hidden;
    transition: all .375s;
}

.main-nav.is-open {
    opacity: 1;
    z-index: 100;
    visibility: visible;
}

/* Yellow band effect */
.main-nav::before {
   content: '';
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: -15px;
    background: #FEDC2A;
    transform-origin: 0 0;
    transform: skew(-14deg) translateX(-120%);
    transition: all .275s .1s;
}

.main-nav.is-open::before {
    transform: skew(-14deg) translateX(0);
}

/* Skewing effect on menu links */
.main-nav ul {
    display: inline-flex;
    flex-direction: column;
    height: 93%; /* Should be 100%, but we have a notice message :D */
    align-items: flex-end;
    justify-content: center;
    transform: translateX(-18%) skew(-16deg);
}

.main-nav li {
    display: block;
    margin: .5rem 0;
    text-align: right;
    transform: skew(16deg);
}

/* Apparition effect on links */
.main-nav a {
    opacity: 0;
    transform: translateY(-10px);
}

.main-nav.is-open a {
    opacity: 1;
    transform: translateY(0);
}
.main-nav li:nth-child(1) a {
  transition: all 275ms 175ms
}
.main-nav li:nth-child(2) a {
  transition: all 275ms 225ms
}
.main-nav li:nth-child(3) a {
  transition: all 275ms 275ms
}
.main-nav li:nth-child(4) a {
  transition: all 275ms 325ms
}
.main-nav li:nth-child(5) a {
  transition: all 275ms 375ms
}


/* Decoration */
.main-nav ul,
.main-nav li {
  list-style: none;
  padding: 0;
}
.main-nav a {
  display: block;
  padding: 12px 0;
  color: #5A3B5D;
  font-size: 1.4em;
  text-decoration: none;
  font-weight: bold;
}

/* Burger Style: @see: https://codepen.io/CreativeJuiz/full/oMZNXy */
.open-main-nav {
  position: absolute;
  top: 15px;
  padding-top: 20px;
  right: 15px;
  z-index: 1000;
  background: none;
  border: 0;
  cursor: pointer;
}
.open-main-nav:focus {
  outline: none;
}
.burger {
  position: relative;
  display: block;
  width: 28px;
  height: 4px;
  margin: 0 auto;
  background: #5A3B5D;
  transform: skew(5deg);
  transition: all .275s;
}

.burger:after,
.burger:before {
  content: '';
  display: block;
  height: 100%;
  background: #5A3B5D;
  transition: all .275s;
}

.burger:after {
  transform: translateY(-12px) translateX(-2px) skew(-20deg);
}

.burger:before {
  transform: translateY(-16px) skew(-10deg);
}

/* Toggle State part */
.is-open .burger {
  transform: skew(5deg) translateY(-8px) rotate(-45deg);
}

.is-open .burger:before {
  transform: translateY(0px) skew(-10deg) rotate(75deg);
}

.is-open .burger:after {
  transform: translateY(-12px) translateX(10px) skew(-20deg);
    opacity: 0;
}

/* MENU Text part */

.burger-text {
  display: block;
  font-size: .675rem;
  letter-spacing: .05em;
  margin-top: .5em;
  text-transform: uppercase;
  font-weight: 500;
  text-align: center;
  color: #5A3B5D;
}

.device {
  position: relative;
  width: 345px;
  height: 600px;
  background: #FFF;
  border: 1px solid #EEE;
  border-radius: 3px;
  box-shadow: 0 0 0 10px rgba(0,0,0,.1);
}

.container {
  position: absolute;
  top: 0; right: 0;
  bottom: 0; left: 0;
  overflow: hidden;
  background: linear-gradient(to bottom, #eee, #ddd);
}

html {
  height: 100%;
}
body {
  height: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
}

/* Slow motion button */
[id="slowmo"] {
  position: absolute;
  top: 20px;
  right: 20px;
  padding: 10px;
  border: 0;
  font-size: 1rem;
  background: #FEDC2A;
  color: #5A3B5D;
  font-weight: bold;
  cursor: pointer;
  transition: all .275s;
}

[id="slowmo"] span {
  display: block;
  font-weight: normal;
}

[id="slowmo"]:hover,
[id="slowmo"]:focus {
  background: #5A3B5D;
  color: #FEDC2A;
}

[id="slowmo"].is-slowmo span:after {
  content: 'Activated';
  display: block;
  font-weight: bold;
}

/* When slowmotion is activated */

.is-slowmo + .device .open-main-nav .burger,
.is-slowmo + .device .open-main-nav .burger:before,
.is-slowmo + .device .open-main-nav .burger:after,
.is-slowmo + .device .main-nav,
.is-slowmo + .device .main-nav::before,
.is-slowmo + .device .main-nav a {
  transition-duration: 3s;
}
.is-slowmo + .device .main-nav li:nth-child(1) a {
  transition-delay: 1750ms
}
.is-slowmo + .device .main-nav li:nth-child(2) a {
  transition-delay: 2250ms
}
.is-slowmo + .device .main-nav li:nth-child(3) a {
  transition-delay: 2750ms
}
.is-slowmo + .device .main-nav li:nth-child(4) a {
  transition-delay: 3250ms
}
.is-slowmo + .device .main-nav li:nth-child(5) a {
  transition-delay: 3750ms
}

/* Notice */
.notice {
  position: absolute;
  bottom: -15px;
  left: 0; right: 0;
  padding: 20px;
  background: #F2F2F2;
  color: #5A3B5D;
  font-size: 14px;
  font-weight: 400;
  line-height: 1.5;
  z-index: 100;
  text-align: center;
}
.notice strong {
  font-weight: 700;
}
.notice a {
  padding: 2px 3px;
  background: #FEDC2A;
  text-decoration: none;
}

let burger = document.getElementById('burger'),
   nav    = document.getElementById('main-nav'),
   slowmo = document.getElementById('slowmo');

burger.addEventListener('click', function(e){
  this.classList.toggle('is-open');
  nav.classList.toggle('is-open');
});

slowmo.addEventListener('click', function(e){
  this.classList.toggle('is-slowmo');
});

/* Onload demo - dirty timeout */
let clickEvent = new Event('click');

window.addEventListener('load', function(e) {
  slowmo.dispatchEvent(clickEvent);
  burger.dispatchEvent(clickEvent);
  
  setTimeout(function(){
    burger.dispatchEvent(clickEvent);
    
    setTimeout(function(){
      slowmo.dispatchEvent(clickEvent);
    }, 3500);
  }, 5500);
});