/* flip transformation */
.flip-container div.front {
    -moz-transform: perspective(2000px) rotateY(0deg);
    -webkit-transform: perspective(2000px) rotateY(0deg);
    -o-transform: perspective(2000px) rotateY(0deg);
    transform: perspective(2000px) rotateY(0deg);
}

    .flip-container div.front.flip {
        -moz-transform: perspective(2000px) rotateY(179.9deg);
        -webkit-transform: perspective(2000px) rotateY(179.9deg);
        -o-transform: perspective(2000px) rotateY(179.9deg);
        transform: perspective(2000px) rotateY(179.9deg);
    }

.flip-container div.back {
    -moz-transform: perspective(2000px) rotateY(-180deg);
    -webkit-transform: perspective(2000px) rotateY(-180deg);
    -o-transform: perspective(2000px) rotateY(-180deg);
    transform: perspective(2000px) rotateY(-180deg);
}

    .flip-container div.back.flip {
        -moz-transform: perspective(2000px) rotateY(0deg);
        -webkit-transform: perspective(2000px) rotateY(0deg);
        -ms-transform: perspective(2000px) rotateY(0);
        -o-transform: perspective(2000px) rotateY(0);
        transform: perspective(2000px) rotateY(0);
    }