Pure CSS / CSS3 Fullscreen Navigation with Hamburger Toggle

Uses CSS3 and checkbox tricks to create a fullscreen navigation that pops out from the center of your webpage.

How to use it:

The html structure to create a pop out navigation with a hamburger toggle.

<div class="outer-menu">
  <input class="checkbox-toggle" type="checkbox" />
  <div class="hamburger">
    <div></div>
  </div>
  <div class="menu">
    <div>
      <div>
        <ul>
          <li><a href="#">Home</a></li>
          <li><a href="#">Servicess</a></li>
          <li><a href="#">About</a></li>
          <li><a href="#">Contact</a></li>
        </ul>
      </div>
    </div>
  </div>
</div>

The required to style the hamburger toggle and make it act as a trigger to toggle the fullscreen navigation.

.outer-menu .checkbox-toggle {
  position: absolute;
  top: 0;
  left: 0;
  z-index: 2;
  cursor: pointer;
  width: 60px;
  height: 60px;
  opacity: 0;
}
.outer-menu .checkbox-toggle:checked + .hamburger > div {
  -webkit-transform: rotate(135deg);
  -ms-transform: rotate(135deg);
  transform: rotate(135deg);
}
.outer-menu .checkbox-toggle:checked + .hamburger > div:before,
.outer-menu .checkbox-toggle:checked + .hamburger > div:after {
  top: 0;
  -webkit-transform: rotate(90deg);
  -ms-transform: rotate(90deg);
  transform: rotate(90deg);
}
.outer-menu .checkbox-toggle:checked + .hamburger > div:after { opacity: 0; }
.outer-menu .checkbox-toggle:checked ~ .menu > div {
  width: 200vw;
  height: 200vw;
}
.outer-menu .checkbox-toggle:checked ~ .menu > div > div {
  opacity: 1;
  -webkit-transition: opacity 0.3s ease 0.3s;
  transition: opacity 0.3s ease 0.3s;
}
.outer-menu .checkbox-toggle:hover + .hamburger { box-shadow: inset 0 0 10px rgba(0, 0, 0, 0.1); }
.outer-menu .checkbox-toggle:checked:hover + .hamburger > div {
  -webkit-transform: rotate(225deg);
  -ms-transform: rotate(225deg);
  transform: rotate(225deg);
}
.outer-menu .hamburger {
  position: absolute;
  top: 0;
  left: 0;
  z-index: 1;
  width: 60px;
  height: 60px;
  padding: .5em 1em;
  background: rgba(33, 150, 243, 0.75);
  border-radius: 0 0.12em 0.12em 0;
  cursor: pointer;
  -webkit-transition: box-shadow 0.3s ease;
  transition: box-shadow 0.3s ease;
  -webkit-backface-visibility: hidden;
  backface-visibility: hidden;
  display: -webkit-box;
  display: -webkit-flex;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-align: center;
  -webkit-align-items: center;
  -ms-flex-align: center;
  align-items: center;
  -webkit-box-pack: center;
  -webkit-justify-content: center;
  -ms-flex-pack: center;
  justify-content: center;
}
.outer-menu .hamburger > div {
  position: relative;
  -webkit-box-flex: 0;
  -webkit-flex: none;
  -ms-flex: none;
  flex: none;
  width: 100%;
  height: 2px;
  background: #fefefe;
  -webkit-transition: all 0.3s ease;
  transition: all 0.3s ease;
  display: -webkit-box;
  display: -webkit-flex;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-align: center;
  -webkit-align-items: center;
  -ms-flex-align: center;
  align-items: center;
  -webkit-box-pack: center;
  -webkit-justify-content: center;
  -ms-flex-pack: center;
  justify-content: center;
}
.outer-menu .hamburger > div:before,
.outer-menu .hamburger > div:after {
  content: '';
  position: absolute;
  z-index: 1;
  top: -10px;
  left: 0;
  width: 100%;
  height: 2px;
  background: inherit;
  -webkit-transition: all 0.3s ease;
  transition: all 0.3s ease;
}
.outer-menu .hamburger > div:after { top: 10px; }

Style the fullscreen navigation.

.outer-menu .menu {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  display: -webkit-box;
  display: -webkit-flex;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-align: center;
  -webkit-align-items: center;
  -ms-flex-align: center;
  align-items: center;
  -webkit-box-pack: center;
  -webkit-justify-content: center;
  -ms-flex-pack: center;
  justify-content: center;
}
.outer-menu .menu > div {
  width: 0;
  height: 0;
  color: #fefefe;
  background: rgba(41, 98, 255, 0.97);
  border-radius: 50%;
  -webkit-transition: all 0.3s ease;
  transition: all 0.3s ease;
  -webkit-box-flex: 0;
  -webkit-flex: none;
  -ms-flex: none;
  flex: none;
  display: -webkit-box;
  display: -webkit-flex;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-align: center;
  -webkit-align-items: center;
  -ms-flex-align: center;
  align-items: center;
  -webkit-box-pack: center;
  -webkit-justify-content: center;
  -ms-flex-pack: center;
  justify-content: center;
}
.outer-menu .menu > div > div {
  text-align: center;
  max-width: 90vw;
  max-height: 100vh;
  opacity: 0;
  -webkit-transition: opacity 0.3s ease;
  transition: opacity 0.3s ease;
  overflow-y: auto;
  -webkit-box-flex: 0;
  -webkit-flex: none;
  -ms-flex: none;
  flex: none;
  display: -webkit-box;
  display: -webkit-flex;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-align: center;
  -webkit-align-items: center;
  -ms-flex-align: center;
  align-items: center;
  -webkit-box-pack: center;
  -webkit-justify-content: center;
  -ms-flex-pack: center;
  justify-content: center;
}
.outer-menu .menu > div > div > ul {
  list-style: none;
  padding: 0 1em;
  margin: 0;
  display: block;
  max-height: 100vh;
}
.outer-menu .menu > div > div > ul > li {
  padding: 0;
  margin: 1em;
  font-size: 24px;
  display: block;
}
.outer-menu .menu > div > div > ul > li > a {
  position: relative;
  display: inline;
  cursor: pointer;
  -webkit-transition: color 0.3s ease;
  transition: color 0.3s ease;
}
.outer-menu .menu > div > div > ul > li > a:hover { color: #e5e5e5; }
.outer-menu .menu > div > div > ul > li > a:hover:after { width: 100%; }
.outer-menu .menu > div > div > ul > li > a:after {
  content: '';
  position: absolute;
  z-index: 1;
  bottom: -0.15em;
  left: 0;
  width: 0;
  height: 2px;
  background: #e5e5e5;
  -webkit-transition: width 0.3s ease;
  transition: width 0.3s ease;
}