Hamburger menu "open/close" icon

hamburger.css

body {
  height: 100%;
  background: #262626;
}
.hamburger {
  position: absolute;
  top: 50%; 
  left: 50%;
  margin: auto;
  width: 60px;
  height: 45px;
  cursor: pointer;
  -webkit-transition: .5s ease-in-out;
  transition: .5s ease-in-out;
  -webkit-transform: rotate(0);
  -ms-transform: rotate(0);
  transform: rotate(0);
}
.hamburger span {
  position: absolute;
  left: 0;
  display: block;
  width: 100%;
  height: 9px;
  border-radius: 9px;
  background: #fff;
  opacity: 1;
  -webkit-transition: .25s ease-in-out;
  transition: .25s ease-in-out;
  -webkit-transform: rotate(0);
  -ms-transform: rotate(0);
  transform: rotate(0);
}
.hamburger span:nth-child(1) { top: 0; }
.hamburger span:nth-child(2), .hamburger span:nth-child(3) { top: 18px; }
.hamburger span:nth-child(4) { top: 36px; }
.hamburger.open span:nth-child(1) {
  top: 18px;
  left: 50%;
  width: 0%;
}
.hamburger.open span:nth-child(2) {
  -webkit-transform: rotate(45deg);
  -ms-transform: rotate(45deg);
  transform: rotate(45deg);
}
.hamburger.open span:nth-child(3) {
  -webkit-transform: rotate(-45deg);
  -ms-transform: rotate(-45deg);
  transform: rotate(-45deg);
}
.hamburger.open span:nth-child(4) {
  top: 18px;
  left: 50%;
  width: 0;
}

index.htm

<div class="hamburger">
  <span></span>
  <span></span>
  <span></span>
  <span></span>
</div>

script.js

$(document).ready(function(){
  $(".hamburger").click(function(){
    $(this).toggleClass("open");
  });
});