do-columns.scss

@mixin do-columns($width-list) {
  & {
    width: 100%;
    font-size: 0;
  }

  >* {
    @include ext_default-font-size;
    display: inline-block;
    vertical-align: top;
    box-sizing: border-box;
  }

  @for $i from 1 through length($width-list) {
    $width: nth($width-list, $i);
    >*:nth-child(#{$i}) { width: calc(#{unquote($width)});}
  }
}