@mixin shape-style($size) {
    @include borders();
    @include border-radius($btn-radius);

    background-color:transparent;

    // Biseau
    position: relative;
    z-index:1;
    overflow: visible;
    &:before {
        content: " ";
        position: absolute;
        top:0;
        left:-$size/2;
        right:-$size/2;
        bottom:0;
        z-index:-1;
        transform: skewX(-15deg);
    }
}

@mixin colorize-shape($background-color) {
    &:before {
        background-color: $background-color;
    }
}