@for $i from 1 through length($breakpoints) {

$breakpoint: nth($breakpoints, $i);
$size: nth($screen-sizes, $i);

@for $i from 1 through $col-total {
  $percent: (100% / $col-total) * $i;
  .offset-#{$i} {
    margin-left: $percent;
  }
}

@media (min-width: $breakpoint) {
  @for $i from 1 through $col-total {
    $percent: (100% / $col-total) * $i;
    .offset-#{$size}-#{$i} {
      margin-left: $percent;
    }
  }
}

}