<div class="nav-menu">
  <h2>menu</h2>
</div>
<div class="main-content center">
  <h1>Welcome to my full page slide down menu</h1>
</div>
<nav class="menu-container">
  <div class="menu-content center">
    <ul class="list-items">
      <li>home</li>
      <li>about</li>
      <li>portfolio</li>
      <li>contact</li>
    </ul>
  </div>
</nav>

* {
  margin: 0;
  padding: 0;
  color: #fff;
}

body {
  font-family: sans-serif;
  background: #2b2769;
  text-align: center;
}

.main-content {
  font-size: 30px
}

.nav-menu{
  z-index: 5;
  position: absolute;
  top: 20px;
  right: 30px;
  cursor: pointer;
}
.menu-container {
  z-index:1;
  position:fixed;
  height: 100%;
  width: 100%;
  background: #E94444;
 }

.center {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}
li {
  list-style-type: none;
  font-size: 50px;
  margin-bottom: 20px;
  font-weight: bold;
}

var menuIcon = $(".nav-menu");  
var menuToggle = new TimelineMax({paused:true, reversed:true});
var slideDown = $(".menu-container");
var listItems = $(".list-items > li");

TweenMax.set(slideDown, {
      y: '-100%'
  });

// TweenMax.set(listItems, {
//       y: '0'
//   });

menuToggle  
  .to(menuIcon, .5, {
  x:'-30',
  ease: Back.easeOut
  // ease: Back.easeIn.config(2.2)
  })
  .to(slideDown, 1, {
  y: '0%',
  ease: Back.easeOut
  })
  .staggerFrom(listItems, .25, {
    y: '-30',
    ease: Power1.easeOut
  }, .1);

menuIcon.click(function () {
  menuToggle.reversed() ? menuToggle.restart() : menuToggle.reverse();
});