<div id="container">
<ul id="menu">
  <li><a href="#">About Me</a>
    <ul>
      <li><a href="#">Lorem ipsum dolor</a></li>
      <li><a href="#">Maecenas lacinia sem</a></li>
      <li><a href="#">Suspendisse fringilla</a></li>
    </ul>
  </li>
  <li><a href="#">Portfolio</a>
    <ul>
      <li><a href="#">Lorem ipsum dolor</a></li>
      <li><a href="#">Maecenas dignissim fermentum luctus</a></li>
      <li><a href="#">Suspendisse fringilla</a></li>
      <li><a href="#">Lorem ipsum dolor</a></li>
      <li><a href="#">Maecenas lacinia sem</a></li>
      <li><a href="#">Suspendisse fringilla</a></li>
    </ul>
  </li>
  <li><a href="#">Clients</a>
    <ul>
      <li><a href="#">Lorem ipsum dolor</a></li>
      <li><a href="#">Maecenas lacinia sem</a></li>
      <li><a href="#">Suspendisse fringilla</a></li>
    </ul>
  </li>
  <li><a href="#">Contact Me</a>
    <ul>
      <li><a href="#">Lorem ipsum dolor</a></li>
      <li><a href="#">Maecenas dignissim fermentum luctus</a></li>
      <li><a href="#">Suspendisse fringilla</a></li>
    </ul>
  </li>
  <li><a href="#">Support</a></li>
</ul>
</div>

* {
    margin: 0; 
    padding: 0;
    box-sizing: border-box;
  }

  body {
    padding: 30px; 
    font-family: "Helvetica Neue", helvetica, arial; 
    background: url('https://subtlepatterns.com/patterns/white_carbonfiber.png');
  }

  #container {
    position: relative;
    width: 940px;   
  }

  #container:after {
    content: "";
    display: block;
    clear: both;
    height: 0;
  }

  #menu {
    position: relative;
    float: left;
    width: 100%;
    padding: 0 20px;
    border-radius: 3px;
    box-shadow: inset 0 1px 1px rgba(255,255,255,.5), inset 0 -1px 0 rgba(0,0,0,.15), 0 1px 3px rgba(0,0,0,.15);
    background: #ccc; 
  }

  #menu, #menu ul {
    list-style: none;
  }

  #menu > li {
    float: left;
    position: relative;
    border-right: 1px solid rgba(0,0,0,.1);
    box-shadow: 1px 0 0 rgba(255,255,255,.25);
    perspective: 1000px;
    
  }

  #menu > li:first-child {
    border-left: 1px solid rgba(255,255,255,.25);
    box-shadow: -1px 0 0 rgba(0,0,0,.1), 1px 0 0 rgba(255,255,255,.25);
  }

  #menu a {
    display: block;
    position: relative;
    z-index: 10;
    padding: 13px 20px 13px 20px;
    text-decoration: none;
    color: rgba(75,75,75,1);
    line-height: 1;
    font-weight: 600;
    font-size: 12px;
    letter-spacing: -.05em;
    background: transparent;    
    text-shadow: 0 1px 1px rgba(255,255,255,.9);
    transition: all .25s ease-in-out;
  
  }

  #menu > li:hover > a {
    background: #333;
    color: rgba(0,223,252,1);
    text-shadow: none;
  }

  #menu li ul  {
    position: absolute;
    left: 0;
    z-index: 1;
    width: 200px;
    padding: 0;
    opacity: 0;
    visibility: hidden;
    border-bottom-left-radius: 4px;
    border-bottom-right-radius: 4px;
    background: transparent;
    overflow: hidden;
    transform-origin: 50% 0%;
  }


  #menu li:hover ul {
    
    padding: 15px 0;
    background: #333;
    opacity: 1;
    visibility: visible;
    box-shadow: 1px 1px 7px rgba(0,0,0,.5);
    animation-name: swingdown;
    animation-duration: 1s;
    animation-timing-function: ease;

  }

  @keyframes swingdown {
    0% {
      opacity: .99999;
      transform: rotateX(90deg);
    }

    30% {     
      transform: rotateX(-20deg) rotateY(5deg);
      animation-timing-function: ease-in-out;
    }

    65% {
      transform: rotateX(20deg) rotateY(-3deg);
      animation-timing-function: ease-in-out;
    }

    100% {
      transform: rotateX(0);
      animation-timing-function: ease-in-out;
    }
  }

  #menu li li a {
    padding-left: 15px;
    font-weight: 400;
    color: #ddd;
    text-shadow: none;
    border-top: dotted 1px transparent;
    border-bottom: dotted 1px transparent;
    transition: all .15s linear;
  }

  #menu li li a:hover {
    color: rgba(0,223,252,1);
    border-top: dotted 1px rgba(255,255,255,.15);
    border-bottom: dotted 1px rgba(255,255,255,.15);
    background: rgba(0,223,252,.02);
  }