Simple SASS grid/columns using mixins

grid.sass

=row()
  font-size: 0

=col($col, $sum, $gap: 1em, $align: top, $first: false, $last: false)
  width: percentage($col/$sum)
  vertical-align: $align
  font-size: $base-font-size
  display: inline-block

  @if $first == false
    padding-left: $gap

  @if $last == false
    padding-right: $gap