* {
  margin: 0;
  padding: 0; 
}


#nav-icon {
  width: 60px;
  height: 45px;
  position: relative;
  margin: 50px auto;
  -webkit-transform: rotate(0deg);
  -moz-transform: rotate(0deg);
  -o-transform: rotate(0deg);
  transform: rotate(0deg);
  -webkit-transition: .5s ease-in-out;
  -moz-transition: .5s ease-in-out;
  -o-transition: .5s ease-in-out;
  transition: .5s ease-in-out;
  cursor: pointer;
}

#nav-icon span {
  display: block;
  position: absolute;
  height: 9px;
  width: 100%;
  background: #bbb;
  border-radius: 9px;
  opacity: 1;
  left: 0;
  -webkit-transform: rotate(0deg);
  -moz-transform: rotate(0deg);
  -o-transform: rotate(0deg);
  transform: rotate(0deg);
  -webkit-transition: .25s ease-in-out;
  -moz-transition: .25s ease-in-out;
  -o-transition: .25s ease-in-out;
  transition: .25s ease-in-out;
}

#nav-icon span:nth-child(1) {
  top: 0px;
}

#nav-icon span:nth-child(2),#nav-icon span:nth-child(3) {
  top: 18px;
}

#nav-icon span:nth-child(4) {
  top: 36px;
}

#nav-icon.open span:nth-child(1) {
  top: 18px;
  width: 0%;
  left: 50%;
}

#nav-icon.open span:nth-child(2) {
  -webkit-transform: rotate(45deg);
  -moz-transform: rotate(45deg);
  -o-transform: rotate(45deg);
  transform: rotate(45deg);
}

#nav-icon.open span:nth-child(3) {
  -webkit-transform: rotate(-45deg);
  -moz-transform: rotate(-45deg);
  -o-transform: rotate(-45deg);
  transform: rotate(-45deg);
}

#nav-icon.open span:nth-child(4) {
  top: 18px;
  width: 0%;
  left: 50%;
}