$grid-columns: 12;

@mixin col($number, $gutter) {
  width: calc(
    99.9% * 1 / #{$number} - (#{$gutter} - #{$gutter} * 1 / #{$number})
  );
  float: left;
  margin-bottom: $gutter;

  &:nth-child(1n) {
    float: left;
    margin-right: $gutter;
    clear: none;
  }
  &:last-child {
    margin-right: 0;
  }
  &:nth-child(#{$number}n) {
    margin-right: 0;
    float: right;
  }
  &:nth-child(#{$number}n + 1) {
    clear: both;
  }
}

@mixin col-width($number, $gutter) {
  width: calc(
    99.9% * 1 / #{$number} - (#{$gutter} - #{$gutter} * 1 / #{$number})
  );
}