body,
#container {
    width: 100%;
    height: 100%;
    background: #1d1e1a;
    margin: 0;
    padding: 0;
}

#skull {
    display:block;
    width: 400px;
    height: 545px;
    margin: auto;
}

polygon {
    stroke: #dbdad7;
    stroke-width: 1px;
}

#skull:hover #jaw {
    transform-origin: top center;
    animation: jabber .35s ease infinite;
}

@keyframes jabber {
    0%, 50%, 100% { transform: rotateZ(0deg) translateY(0px); }
    33% { top: 1px; transform: rotateZ(-.5deg) translateY(10px); }
    66% { top: 1px; transform: rotateZ(.5deg) translateY(8px); }
}