アイコンがアニメーションするドロワメニュー #CSS

ちょっと気になったので、作ってみた。
ハンバーガーアイコン　-> ☓ボタン

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Document</title>
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.4/jquery.min.js"></script>
</head>
<body>
  <nav class="toggle-menu">
    <div class="menu-contents">
    </div>
    <div class="hum-icon">
      <div class="hum"></div>
    </div>
  </nav>
  <div class="main-contents">
    <div class="nav-bar"></div>
  </div>

<style>
  html,body{
    height: 100%;
    margin: 0;
  }
  .toggle-menu{
    display: block;
    min-height: 100%;
    width: 300px;
    background-color: #E91E63;
    position: absolute;
    top: 0;
    left: 0;
    -webkit-transform: translateX(-300px);
    transform: translateX(-300px);
    -webkit-transition:ease 0.5s;
    transition:ease 0.5s;
    z-index:9999;
  }
  .open{
    -webkit-transform: translateX(0px);
    transform: translateX(0px);
    box-shadow:0px 0px 3px;
  }
  .hum-icon{
    display:block;
    height: 40px;
    width: 40px;
    position:fixed;
    top:5px;
    left:305px;
    cursor: pointer;
    -webkit-transition:ease 0.5s;
    transition:ease 0.5s;
  }
  .open-icon{
    -webkit-transform: translateX(-45px);
    transform: translateX(-45px);
  }
  .hum{
    display:block;
    position: absolute;
    top: 35%;
    height: 2px;
    width: 100%;
    background-color: #555;
    -webkit-transition:ease 0.3s;
    transition:ease 0.3s;
  }
  .hum.cross-mark{
    width: 0;
    background-color: white;
  }
  .hum-icon:before{
    content: '';
    position: absolute;
    top: 15%;
    width: 100%;
    height: 2px;
    background-color: #555;
    -webkit-transition:ease 0.5s;
    transition:ease 0.5s;
  }
  .hum-icon.open-icon:before{
    transform: rotate(-45deg);
    background-color: white;
    top: 45%;
  }
  .hum-icon:after{
    content: '';
    position: absolute;
    top: 55%;
    width: 100%;
    height: 2px;
    background-color: #555;
    -webkit-transition:ease 0.5s;
    transition:ease 0.5s;
  }
  .hum-icon.open-icon:after{
    transform: rotate(45deg);
    background-color: white;
    top: 45%;
  }
  .nav-bar{
    width: 100%;
    height:40px;
    box-shadow: 0px 0px 1px;
  }

</style>
<script>
  $(function(){
    $('.hum-icon').click(function(){
      $('.toggle-menu').toggleClass('open');
      $(this).toggleClass('open-icon');
      $('.hum,hum-icon').toggleClass('cross-mark');
    });
  });
</script>
</body>
</html>