$grid-columns: 12;

@mixin make-col($size, $columns: $grid-columns) {
    flex: 0 0 percentage(math.div($size, $columns));
    // Add a `max-width` to ensure content within each column does not blow out
    // the width of the column. Applies to IE10+ and Firefox. Chrome and Safari
    // do not appear to require this.
    max-width: percentage(math.div($size, $columns));
}