@mixin flip($selector: ".flipped", $duration: 0.5s, $delay: 0s, $fill-mode: both, $count: 1, $timing: ease-in) {
    position: relative;
    @include u-prefix(transform-style, preserve-3d, webkit spec);
    @include u-transition(all $duration $delay $timing);
    @include u-prefix(backface-visibility, hidden, webkit moz spec);
    &#{$selector} {
        @include u-transform(rotateY(180deg) translateZ(0));
    }
    &::after {
        content: '';
        position: absolute;
        left: 0;
        height: 100%;
        width: 100%;
        @include u-prefix(backface-visibility, inherit, webkit moz spec);
        @include u-transform(rotateY(180deg));
    }
}