docker-php/docs/assets/css/hamburger.css

#nav-icon span {
    display: block;
    position: absolute;
    height: 2px;
    width: 50%;
    background: #FFF;
    opacity: 1;
    -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(even) {
    left: 50%;
    border-radius: 0 9px 9px 0;
}

#nav-icon span:nth-child(odd) {
    left:0px;
    border-radius: 9px 0 0 9px;
}

#nav-icon span:nth-child(1), #nav-icon span:nth-child(2) {
    top: 0px;
}

#nav-icon span:nth-child(3), #nav-icon span:nth-child(4) {
    top: 6px;
}

#nav-icon span:nth-child(5), #nav-icon span:nth-child(6) {
    top: 12px;
}

#nav-icon.open span:nth-child(1),#nav-icon.open span:nth-child(6) {
    -webkit-transform: rotate(45deg);
    -moz-transform: rotate(45deg);
    -o-transform: rotate(45deg);
    transform: rotate(45deg);
}

#nav-icon.open span:nth-child(2),#nav-icon.open span:nth-child(5) {
    -webkit-transform: rotate(-45deg);
    -moz-transform: rotate(-45deg);
    -o-transform: rotate(-45deg);
    transform: rotate(-45deg);
}

#nav-icon.open span:nth-child(1) {
    left: 3px;
    top: 3px;
}

#nav-icon.open span:nth-child(2) {
    left: calc(50%);
    top: 3px;
}

#nav-icon.open span:nth-child(3) {
    left: -50%;
    opacity: 0;
}

#nav-icon.open span:nth-child(4) {
    left: 100%;
    opacity: 0;
}

#nav-icon.open span:nth-child(5) {
    left: 3px;
    top: 10px;
}

#nav-icon.open span:nth-child(6) {
    left: calc(50%);
    top: 10px;
}