utilities.less

.sprite(@pos-x; @pos-y; @repeat: no-repeat) {
    background: url("../images/sprite.png") @pos-x @pos-y @repeat;

    @media only screen and (-webkit-min-device-pixel-ratio: 2),
        only screen and (   min--moz-device-pixel-ratio: 2),
        only screen and (     -o-min-device-pixel-ratio: 2/1),
        only screen and (        min-device-pixel-ratio: 2),
        only screen and (                min-resolution: 192dpi),
        only screen and (                min-resolution: 2dppx) {
            background-size: 500px 500px;
            background-image: url('../images/sprite2x.png');
        }
}


.make-grid(@cols, @margin) {
    width: ((100% - ((@cols - 1) * @margin)) / @cols);

    & {
        margin-left: @margin;
    }
    &:nth-child(@{cols}n + 1) {
        margin-left: 0;
    }
}