Extended mixin to scale zoomed image

gistfile1.css

@boundaryScale: 2;
.zoomStep(@zoomFactor) {
    @boundarySize: (@boundaryScale * @zoomFactor);
    .zoomBoundary {
        width: @boundarySize;
        height: @boundarySize;
        top:  (0 - (@boundarySize - 100%)/2);
        left: (0 - (@boundarySize - 100%)/2);
    }
    @imgPrimaryDimensionSize: ((100% + ((@boundarySize - 100%)/2)) / (@boundarySize/100));
    .zoomBoundary {
        .zoomImg {
            width: @imgPrimaryDimensionSize - 1%;
            height: @imgPrimaryDimensionSize - 1%;
            left: ((100% - (@imgPrimaryDimensionSize - 1%)) /2);
            top:  ((100% - (@imgPrimaryDimensionSize - 1%)));
        }
    }
}