.burger{
  width: 40px;
  height: 26px;
  -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;
}
.burger span{
  display: block;
  position: absolute;
  height: 6px;
  width: 100%;
  background: #fff;
  border-radius: 0px;
  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;
}
.burger span:nth-child(1) {
  top: 0px;
}
.burger span:nth-child(2),.burger span:nth-child(3) {
  top: 10px;
}
.burger span:nth-child(4) {
  top: 20px;
}
.burger.open span:nth-child(1) {
  top: 10px;
  width: 0%;
  left: 50%;
}
@media screen and (max-width: 768px) {
  .burger{
    width: 30px;
  }
  .burger span{
    height: 4px;
  }
}
.burger.open span:nth-child(2) {
  -webkit-transform: rotate(45deg);
  -moz-transform: rotate(45deg);
  -o-transform: rotate(45deg);
  transform: rotate(45deg);
}
.burger.open span:nth-child(3) {
  -webkit-transform: rotate(-45deg);
  -moz-transform: rotate(-45deg);
  -o-transform: rotate(-45deg);
  transform: rotate(-45deg);
}
.burger.open span:nth-child(4) {
  top: 10px;
  width: 0%;
  left: 50%;
}