<body>
<label>
<input type="checkbox">
<span class="menu"> <span class="hamburger"></span> </span>
<ul>
  <li> <a href="#">Home</a> </li>
  <li> <a href="#">About</a> </li>
  <li> <a href="#">Contact</a> </li>
</ul>
</label>
<h1>Morphing Fullscreen Hamburger Menu Demo</h1>
</body>


*, *:before, *:after 
{ box-sizing: border-box; }

html { font-size: 18px; }

body {
  color: #e0e4cc;
  font-size: 1.2em;
  line-height: 1.6;
  background: #fa6900;
  overflow-x: hidden;
}

label .menu {
  position: absolute;
  right: -100px;
  top: -100px;
  z-index: 100;
  width: 200px;
  height: 200px;
  background: #FFF;
  border-radius: 50% 50% 50% 50%;
  -webkit-transition: .5s ease-in-out;
  transition: .5s ease-in-out;
  box-shadow: 0 0 0 0 #FFF, 0 0 0 0 #FFF;
  cursor: pointer;
  
}

label .hamburger {
  position: absolute;
  top: 135px;
  left: 50px;
  width: 30px;
  height: 2px;
  background: #69D2e7;
  display: block;
  -webkit-transform-origin: center;
  transform-origin: center;
  -webkit-transition: .5s ease-in-out;
  transition: .5s ease-in-out;
}

label .hamburger:after, label .hamburger:before {
  -webkit-transition: .5s ease-in-out;
  transition: .5s ease-in-out;
  content: "";
  position: absolute;
  display: block;
  width: 100%;
  height: 100%;
  background: #69d2e7;
}

label .hamburger:before { top: -10px; }

label .hamburger:after { bottom: -10px; }

label input { display: none; }

label input:checked + .menu {
  box-shadow: 0 0 0 100vw #FFF, 0 0 0 100vh #FFF;
  border-radius: 0;
  
}

label input:checked + .menu .hamburger {
  -webkit-transform: rotate(45deg);
  transform: rotate(45deg);
  
}

label input:checked + .menu .hamburger:after {
  -webkit-transform: rotate(90deg);
  transform: rotate(90deg);
  bottom: 0;
  
}

label input:checked + .menu .hamburger:before {
  -webkit-transform: rotate(90deg);
  transform: rotate(90deg);
  top: 0;
  
}

label input:checked + .menu + ul { opacity: 1; }

label ul {
  z-index: 200;
  position: absolute;
  top: 50%;
  left: 50%;
  -webkit-transform: translate(-50%, -50%);
  transform: translate(-50%, -50%);
  opacity: 0;
  -webkit-transition: .25s 0s ease-in-out;
  transition: .25s 0s ease-in-out;
}

label a {
  margin-bottom: 1em;
  display: block;
  color: #f38630;
  text-decoration: none;
  
}

h1 {
  position: absolute;
  top: 50%;
  left: 50%;
  -webkit-transform: translate(-50%, -50%);
  transform: translate(-50%, -50%);
  width: 80%;
  text-align: center;
}

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

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