You can add a little JavaScript.

Menu.style.display = "none";
function ShowHide(x) {
  x.classList.toggle("change");
  var Menu = document.getElementById("Menu");
  if (Menu.style.display === "none") {
    Menu.style.display = "block";
  } else {
    Menu.style.display = "none";
  }
}

  .container {
    display: inline-block;
    cursor: pointer;
  }

  .bar1, .bar2, .bar3 {
    width: 35px;
    height: 5px;
    background-color: #333;
    margin: 6px 0;
    transition: 0.4s;
  }

  .change .bar1 {
    -webkit-transform: rotate(-45deg) translate(-9px, 6px);
    transform: rotate(-45deg) translate(-9px, 6px);
  }

  .change .bar2 {opacity: 0;}

  .change .bar3 {
    -webkit-transform: rotate(45deg) translate(-8px, -8px);
    transform: rotate(45deg) translate(-8px, -8px);
  }

<div class="container" onclick="ShowHide(this)">
  <div class="bar1"></div>
  <div class="bar2"></div>
  <div class="bar3"></div>
</div>

<div id="Menu" style="width: 150px; background-color: rgb(217, 231, 255); display: none;">
  <h2><a href="#1">Item 1</a></h2>
  <h2><a href="#2">Item 2</a></h2>
  <h2><a href="#3">Item 3</a></h2>
</div>

View on JSFiddle