<!-- @NOTE: the onclicks are used for touch devices since I'm lazy and didnt use <a> tags -->
<div class="Menu">
  <ul class="Menu-list" data-offset="10">
    <li class="Menu-list-item" data-offset="20" onclick>
      Home
      <span class="Mask"><span>Home</span></span>
      <span class="Mask"><span>Home</span></span>
    </li>
    <li class="Menu-list-item" data-offset="16" onclick>
      About
      <span class="Mask"><span>About</span></span>
      <span class="Mask"><span>About</span></span>
    </li>
    <li class="Menu-list-item" data-offset="12" onclick>
      Work
      <span class="Mask"><span>Work</span></span>
      <span class="Mask"><span>Work</span></span>
    </li>
    <li class="Menu-list-item" data-offset="8" onclick>
      Contact
      <span class="Mask"><span>Contact</span></span>
      <span class="Mask"><span>Contact</span></span>
    </li>
  </ul>
</div>

// === Variables =====
$perspective:     60rem;
$font-size:       4.25rem;
$split-position:  49%;
$split-thickness: 4px;
$split-color:     #FF2C75;

// === Settings =====
%font-settings {
  font-family: "Gilroy ExtraBold", system-ui, sans-serif;
  font-style: normal;
  font-weight: normal;
  -webkit-font-smoothing: antialiased;
  -webkit-font-kerning: normal;
  -webkit-text-size-adjust: 100%;
}

// === Codepen Setup =====
html,
body {
  width: 100vw;
  height: 100vh;
}
body {
  @extend %font-settings;
  background: linear-gradient(45deg, #02001F,#1F1B4E);
  transform-style: preserve-3d;
  transform: perspective($perspective);
  position: fixed;
  display: flex;
  align-items: center;
  justify-content: center; 
}

// === Menu <ul> =====
.Menu-list {
  font-size: $font-size;
  line-height: 1.2;
  text-transform: uppercase;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  transform: rotateX(-10deg) rotateY(20deg); // overwritten by JS
}

// === Menu item =====
.Menu-list-item {
  position: relative;
  color: transparent;
  cursor: pointer;
  
  // === Split Line =====
  &::before {
    content: '';
    display: block;
    position: absolute;
    top: $split-position;
    left: -10%;
    right: -10%;
    height: $split-thickness;
    border-radius: $split-thickness;
    margin-top: -($split-thickness / 2);
    background: $split-color;
    transform: scale(0);
    transition: transform .8s cubic-bezier(.16,1.08,.38,.98);
    z-index: 1;
  }
}

// === Top/bottom mask =====
.Mask {
  display: block;
  position: absolute;
  overflow: hidden;
  color: $split-color;
  top: 0;
  height: $split-position;
  transition: all .8s cubic-bezier(.16,1.08,.38,.98);
  
  span { display: block; }
}

// === Bottom mask specific =====
.Mask + .Mask {
  top: $split-position - 0.1;
  height: 100 - $split-position + 0.1;
  
  span { transform: translateY(-$split-position); }
}

// === Where the fun stuff happens =====
.Menu-list-item:hover,
.Menu-list-item:active {
  .Mask { color: #FFF; transform: skewX(12deg) translateX(5px); }
  .Mask + .Mask { transform: skewX(12deg) translateX(-5px); }
  &::before { transform: scale(1); }
}

var $menu = $('.Menu-list'),
    $item = $('.Menu-list-item'),
    w = $(window).width(), //window width
    h = $(window).height(); //window height

$(window).on('mousemove', function(e) {
  var offsetX = 0.5 - e.pageX / w, //cursor position X
      offsetY = 0.5 - e.pageY / h, //cursor position Y
      dy = e.pageY - h / 2, //@h/2 = center of poster
      dx = e.pageX - w / 2, //@w/2 = center of poster
      theta = Math.atan2(dy, dx), //angle between cursor and center of poster in RAD
      angle = theta * 180 / Math.PI - 90, //convert rad in degrees
      offsetPoster = $menu.data('offset'),
      transformPoster = 'translate3d(0, ' + -offsetX * offsetPoster + 'px, 0) rotateX(' + (-offsetY * offsetPoster) + 'deg) rotateY(' + (offsetX * (offsetPoster * 2)) + 'deg)'; //poster transform

  //get angle between 0-360
  if (angle < 0) {
    angle = angle + 360;
  }

  //poster transform
  $menu.css('transform', transformPoster);

  //parallax for each layer
  $item.each(function() {
    var $this = $(this),
        offsetLayer = $this.data('offset') || 0,
        transformLayer = 'translate3d(' + offsetX * offsetLayer + 'px, ' + offsetY * offsetLayer + 'px, 20px)';

    $this.css('transform', transformLayer);
  });
});