simplest-flexbox-grid _fg_grid() mixin

_fg_grid_mixin.scss

/* Usage
pass columns list or column number and optionally gutter and padding
columns list: 1 2 1 => 4 columns altogether:
col 1/4 (25%), then col 2/4 (50%) and finally 1/4 (25%)
@include _fg_grid(1 2 1);
@include _fg_grid(1 2, 32, 24);
@include _fg_grid(1 2, $gutter: 32, $padding: 24);
if a number is passed instead of a list the mixin is equivalent to _fg() mixin
 */
@mixin _fg_grid($colList, $gutter: $_fg_gutter, $padding: $_fg_padding) {

  @if type-of($colList) == number { // call _fg() directly
    @include _fg($colList, $gutter, $padding);

  } @else if type-of($colList) == list and length($colList) > 1 {

    $columnCount: 0;

    @each $i in $colList {  // count how many columns are altogether
      $columnCount: $columnCount + $i;
    }

    @include _fg($columnCount, $gutter, $padding);

    @for $i from 1 through length($colList) { // set child items widths using nth:child()
      $c: nth($colList, $i);
      & > :nth-child(#{$i}) {
        @include _fg_width($c/$columnCount, $gutter);
      }
    }
  }
}