.conteneur_polyedre {
    perspective: 800px;
    perspective-origin: 50% 100px;
    padding: 100px 0;
}
.polyedre {
    position: relative;
    width: 200px;
    height: 200px;
    transform-style: preserve-3d;
}
.polyedre div {
    position: absolute;
    width: 200px;
    height: 200px;
    text-align: center;
    font-size: xx-large;
    background: rgba(0,0,255,0.1);
    /*transform-origin: 100px 100px 0px;*/
}
.face_1 {
    transform: translateZ(137px);
}
.face_2 {
    transform: rotateX(72deg) translateZ(137px);
}
.face_3 {
    transform: rotateX(144deg) translateZ(137px);
}
.face_4 {
    transform: rotateX(216deg) translateZ(137px);
}
.face_5 {
    transform: rotateX(288deg) translateZ(137px);
}
@keyframes spin-vertical {
    from { transform: rotateX(0); }
    to { transform: rotateX(-360deg); }
}
.conteneur_polyedre.vertical .polyedre {
    margin: 0 auto; /* keeps the polyedre centered */
    
    transform-origin: 100px 100px 0px;
    animation: spin-vertical 5s infinite linear;
}