@mixin offsets($col, $columns: null) {
  margin-left: calc(100% - ((100% / #{$columns}) * (#{$columns} - #{$col}))) !important;
}

@mixin dynamic-offset($size: 'xs', $columns: null) {
  @for $i from 1 through $columns {
    &-#{$size}-#{$i} {
      @include offsets(#{$i}, $columns)
    }
  }
}