<input type="checkbox" id="burger-checkbox" class="burger-checkbox">
<label class="burger" for="burger-checkbox"></label>

.burger-checkbox {
  position: absolute;
  visibility: hidden;
}
.burger {
  cursor: pointer;
  display: block;
  position: relative;
  border: none;
  background: transparent;
  width: 40px;
  height: 26px;
  margin: 30px auto;
}
.burger::before,
.burger::after {
  content: '';
  left: 0;
  position: absolute;
  display: block;
  width: 100%;
  height: 4px;
  border-radius: 10px;
  background: #000;
}
.burger::before {
  top: 0;
  box-shadow: 0 11px 0 #000;
  transition: box-shadow .3s .15s, top .3s .15s, transform .3s;
}
.burger::after {
  bottom: 0;
  transition: bottom .3s .15s, transform .3s;
}
.burger-checkbox:checked + .burger::before {
  top: 11px;
  transform: rotate(45deg);
  box-shadow: 0 6px 0 rgba(0,0,0,0);
  transition: box-shadow .15s, top .3s, transform .3s .15s;
}
.burger-checkbox:checked + .burger::after {
  bottom: 11px;
  transform: rotate(-45deg);
  transition: bottom .3s, transform .3s .15s;
}