.spin-burger {
  transform-style: flat;
  animation: burgerSpinFixed 1.15s cubic-bezier(.22,.9,.34,1.15) 1.55s both;
}
@keyframes burgerSpinFixed {
  0% { opacity:0; transform:translate(-50%,55px) rotate(-220deg) scale(.28); }
  25% { opacity:1; }
  72% { opacity:1; transform:translate(-50%,-10px) rotate(310deg) scale(1.12); }
  100% { opacity:1; transform:translate(-50%,0) rotate(360deg) scale(1); }
}