STEP1

</body> 前加入下面這段 javascript 。

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<script type="text/javascript">
    var forEach=function(t,o,r){if("[object Object]"===Object.prototype.toString.call(t))for(var c in t)Object.prototype.hasOwnProperty.call(t,c)&&o.call(r,t[c],c,t);else for(var e=0,l=t.length;l>e;e++)o.call(r,t[e],e,t)};
    var hamburgers = document.querySelectorAll(".hamburger");
    if (hamburgers.length > 0) {
        forEach(hamburgers, function(hamburger) {
            hamburger.addEventListener("click", function() {
              this.classList.toggle("is-active");
            }, false);
        });
    }
</script>

STEP2

加入 CSS 並稍作調整。

.hamburger {
padding: 0;
cursor: pointer;
transition-property: opacity, filter;
transition-duration: 0.15s;
transition-timing-function: linear;
font: inherit;
color: inherit;
text-transform: none;
background-color: transparent;
border: 0;
margin: 0;
overflow: visible; }
.hamburger:hover {
opacity: 0.7; }

.hamburger-box {
width: 40px;
height: 24px;
display: inline-block;
position: relative; }

.hamburger-inner {
display: block;
top: 50%;
margin-top: -2px; }
.hamburger-inner, .hamburger-inner::before, .hamburger-inner::after {
width: 20px;
height: 3px;
background-color: #000;
border-radius: 4px;
position: absolute;
transition-property: transform;
transition-duration: 0.15s;
transition-timing-function: ease; }
.hamburger-inner::before, .hamburger-inner::after {
content: "";
display: block; }
.hamburger-inner::before {
top: -6px; }
.hamburger-inner::after {
bottom: -10px; }

.hamburger--collapse .hamburger-inner {
top: auto;
bottom: 0;
right: 10px;
transition-duration: 0.13s;
transition-delay: 0.13s;
transition-timing-function: cubic-bezier(0.55, 0.055, 0.675, 0.19); }
.hamburger--collapse .hamburger-inner::after {
top: -12px;
transition: top 0.2s 0.2s cubic-bezier(0.33333, 0.66667, 0.66667, 1), opacity 0.1s linear; }
.hamburger--collapse .hamburger-inner::before {
transition: top 0.12s 0.2s cubic-bezier(0.33333, 0.66667, 0.66667, 1), transform 0.13s cubic-bezier(0.55, 0.055, 0.675, 0.19); }

.hamburger--collapse.is-active .hamburger-inner {
transform: translate3d(0, -10px, 0) rotate(-45deg);
transition-delay: 0.22s;
transition-timing-function: cubic-bezier(0.215, 0.61, 0.355, 1); }
.hamburger--collapse.is-active .hamburger-inner::after {
top: 0;
opacity: 0;
transition: top 0.2s cubic-bezier(0.33333, 0, 0.66667, 0.33333), opacity 0.1s 0.22s linear; }
.hamburger--collapse.is-active .hamburger-inner::before {
top: 0;
transform: rotate(-90deg);
transition: top 0.1s 0.16s cubic-bezier(0.33333, 0, 0.66667, 0.33333), transform 0.13s 0.25s cubic-bezier(0.215, 0.61, 0.355, 1); }

STEP3

將此 DIV 放置至漢堡鈕位置。

<button class="hamburger hamburger--collapse" type="button">
    <span class="hamburger-box"> <span class="hamburger-inner"></span> </span>
</button>