* {
  box-sizing: border-box;
}

.burger-button {
  display: block;
  position: relative;
  width: 44px;
  height: 44px;
  border-radius: 5px;
}

.burger-button:before,
.burger-button:after {
  content: '';
  position: absolute;
  display: block;
  height: 1px;
  width: 16px;
  left: 7px;
  background-color: #333;
  transition: all .3s ease-out;
}

.burger-button:before {
  top: 19px;
}

.burger-button:after {
  bottom: 19px;
}

.burger-button:hover:before,
.burger-button:hover:after {
  background-color: #666;
}

.burger-button.active:before,
.burger-button.active:after {
  top: 22px;
}

.burger-button.active:before {
  transform: rotate(45deg);
}

.burger-button.active:after {
  transform: rotate(135deg);
}

Hier geht's zum Klick-Dummy.