Morphing Hamburger Menu With Pure CSS/CSS3

A pretty cool app/site navigation which has the ability to morph the hamburger button into a top navigation panel when clicked/taped. Built using pure CSS and CSS3 animations.

How to use it:

Create the navigation menu:

<nav class="nav">
  <a class="nav-item" href="#">Home</a>
  <a class="nav-item" href="#">Blog</a>
  <a class="nav-item" href="#">About</a>
  <a class="nav-item" href="#">Contact</a>
</nav>

Create the hamburger style menu toggle button using checkbox and label elements as this:

<!-- This checkbox will give us the toggle behavior, it will be hidden, but functional -->
<input id="toggle" type="checkbox">
<!-- IMPORTANT: Any element that we want to modify when the checkbox state changes go here, being "sibling" of the checkbox element -->
<!-- This label is tied to the checkbox, and it will contain the toggle "buttons" -->
<label class="toggle-container" for="toggle">
  <!-- If menu is open, it will be the "X" icon, otherwise just a clickable area behind the hamburger menu icon -->
  <span class="button button-toggle"></span>
</label>

The main CSS styles for the navigation menu.

.nav {
  display: inline-block;
  margin: 25px 25px 20px;
  pointer-events: none;
  -webkit-transition: 0.5s;
  transition: 0.5s;
}
.nav-item {
  position: relative;
  display: inline-block;
  float: left;
  clear: both;
  color: transparent;
  font-size: 14px;
  letter-spacing: -6.2px;
  height: 7px;
  line-height: 7px;
  text-transform: uppercase;
  white-space: nowrap;
  -webkit-transform: scaleY(0.2);
      -ms-transform: scaleY(0.2);
          transform: scaleY(0.2);
  -webkit-transition: 0.5s, opacity 1s;
  transition: 0.5s, opacity 1s;
}
.nav-item:nth-child(1) {
  -webkit-transition-delay: 0s;
          transition-delay: 0s;
}
.nav-item:nth-child(1):before {
  -webkit-transition-delay: 0s;
          transition-delay: 0s;
}
.nav-item:nth-child(2) {
  -webkit-transition-delay: 0.05s;
          transition-delay: 0.05s;
}
.nav-item:nth-child(2):before {
  -webkit-transition-delay: 0.05s;
          transition-delay: 0.05s;
}
.nav-item:nth-child(3) {
  -webkit-transition-delay: 0.1s;
          transition-delay: 0.1s;
}
.nav-item:nth-child(3):before {
  -webkit-transition-delay: 0.1s;
          transition-delay: 0.1s;
}
.nav-item:nth-child(4) {
  -webkit-transition-delay: 0.15s;
          transition-delay: 0.15s;
}
.nav-item:nth-child(4):before {
  -webkit-transition-delay: 0.15s;
          transition-delay: 0.15s;
}
.nav-item:nth-child(1) {
  letter-spacing: -8px;
}
.nav-item:nth-child(2) {
  letter-spacing: -7px;
}
.nav-item:nth-child(n + 4) {
  letter-spacing: -8px;
  margin-top: -7px;
  opacity: 0;
}
.nav-item:before {
  position: absolute;
  content: '';
  top: 50%;
  left: 0;
  width: 100%;
  height: 2px;
  background-color: #EC7263;
  -webkit-transform: translateY(-50%) scaleY(5);
      -ms-transform: translateY(-50%) scaleY(5);
          transform: translateY(-50%) scaleY(5);
  -webkit-transition: 0.5s;
  transition: 0.5s;
}

Style the hamburger menu toggle button.

.button-toggle {
  position: absolute;
  display: inline-block;
  width: 20px;
  height: 20px;
  margin: 25px;
  background-color: transparent;
  border: none;
  cursor: pointer;
  border-radius: 100%;
  -webkit-transition: 0.6s;
  transition: 0.6s;
}
.button-toggle:hover {
  box-shadow: 0 0 0 8px rgba(0, 0, 0, 0.1), inset 0 0 0 20px rgba(0, 0, 0, 0.1);
}
.button-toggle:before, .button-toggle:after {
  position: absolute;
  content: '';
  top: 50%;
  left: 0;
  width: 100%;
  height: 2px;
  background-color: #EC7263;
  border-radius: 5px;
  -webkit-transition: 0.5s;
  transition: 0.5s;
}
.button-toggle:before {
  -webkit-transform: translateY(-50%) rotate(45deg) scale(0);
      -ms-transform: translateY(-50%) rotate(45deg) scale(0);
          transform: translateY(-50%) rotate(45deg) scale(0);
}
.button-toggle:after {
  -webkit-transform: translateY(-50%) rotate(-45deg) scale(0);
      -ms-transform: translateY(-50%) rotate(-45deg) scale(0);
          transform: translateY(-50%) rotate(-45deg) scale(0);
}

The toggle functionality.

#toggle {
  display: none;
}
#toggle:checked ~ .toggle-container .button-toggle {
  box-shadow: 0 0 0 550px rgba(0, 0, 0, 0.1), inset 0 0 0 20px rgba(0, 0, 0, 0.1);
}
#toggle:checked ~ .toggle-container .button-toggle:before {
  -webkit-transform: translateY(-50%) rotate(45deg) scale(1);
      -ms-transform: translateY(-50%) rotate(45deg) scale(1);
          transform: translateY(-50%) rotate(45deg) scale(1);
}
#toggle:checked ~ .toggle-container .button-toggle:after {
  -webkit-transform: translateY(-50%) rotate(-45deg) scale(1);
      -ms-transform: translateY(-50%) rotate(-45deg) scale(1);
          transform: translateY(-50%) rotate(-45deg) scale(1);
}
#toggle:checked ~ .nav {
  margin-bottom: 100px;
  pointer-events: auto;
  -webkit-transform: translate(50px, 50px);
      -ms-transform: translate(50px, 50px);
          transform: translate(50px, 50px);
}
#toggle:checked ~ .nav .nav-item {
  color: #EC7263;
  letter-spacing: 0;
  height: 40px;
  line-height: 40px;
  margin-top: 0;
  opacity: 1;
  -webkit-transform: scaleY(1);
      -ms-transform: scaleY(1);
          transform: scaleY(1);
  -webkit-transition: 0.5s, opacity 0.1s;
  transition: 0.5s, opacity 0.1s;
}
#toggle:checked ~ .nav .nav-item:nth-child(1) {
  -webkit-transition-delay: 0.15s;
          transition-delay: 0.15s;
}
#toggle:checked ~ .nav .nav-item:nth-child(1):before {
  -webkit-transition-delay: 0.15s;
          transition-delay: 0.15s;
}
#toggle:checked ~ .nav .nav-item:nth-child(2) {
  -webkit-transition-delay: 0.1s;
          transition-delay: 0.1s;
}
#toggle:checked ~ .nav .nav-item:nth-child(2):before {
  -webkit-transition-delay: 0.1s;
          transition-delay: 0.1s;
}
#toggle:checked ~ .nav .nav-item:nth-child(3) {
  -webkit-transition-delay: 0.05s;
          transition-delay: 0.05s;
}
#toggle:checked ~ .nav .nav-item:nth-child(3):before {
  -webkit-transition-delay: 0.05s;
          transition-delay: 0.05s;
}
#toggle:checked ~ .nav .nav-item:nth-child(4) {
  -webkit-transition-delay: 0s;
          transition-delay: 0s;
}
#toggle:checked ~ .nav .nav-item:nth-child(4):before {
  -webkit-transition-delay: 0s;
          transition-delay: 0s;
}
#toggle:checked ~ .nav .nav-item:before {
  opacity: 0;
}
#toggle:checked ~ .dummy-content {
  padding-top: 30px;
}
#toggle:checked ~ .dummy-content:before {
  background-color: rgba(0, 0, 0, 0.3);
}