#nav-icon {
    display: none;
    width: 40px;
    height: 30px;
    margin: 5px;
    position: relative;
    -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: 6px;
    width: 100%;
    background: white;
    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;
    -webkit-transform-origin: left center;
    -moz-transform-origin: left center;
    -o-transform-origin: left center;
    transform-origin: left center;
}

#nav-icon span:nth-child(2) {
    top: 12px;
    -webkit-transform-origin: left center;
    -moz-transform-origin: left center;
    -o-transform-origin: left center;
    transform-origin: left center;
}

#nav-icon span:nth-child(3) {
    top: 24px;
    -webkit-transform-origin: left center;
    -moz-transform-origin: left center;
    -o-transform-origin: left center;
    transform-origin: left center;
}

#nav-icon.open span:nth-child(1) {
    -webkit-transform: rotate(45deg);
    -moz-transform: rotate(45deg);
    -o-transform: rotate(45deg);
    transform: rotate(45deg);
    top: -1px;
    left: 5px;
}

#nav-icon.open span:nth-child(2) {
    width: 0%;
    opacity: 0;
}

#nav-icon.open span:nth-child(3) {
    -webkit-transform: rotate(-45deg);
    -moz-transform: rotate(-45deg);
    -o-transform: rotate(-45deg);
    transform: rotate(-45deg);
    top: 28px;
    left: 5px;
}