.menu span{display:block;width:25px;height:2px;background:currentColor;margin:5px 0;transition:.2s}
.menu.active span:nth-child(1){transform:translateY(7px) rotate(45deg)}
.menu.active span:nth-child(2){opacity:0}
.menu.active span:nth-child(3){transform:translateY(-7px) rotate(-45deg)}