Sass default margins and paddings generator.

margins-paddings.scss

$size: 8;

$margins: (mb: margin-bottom, mt: margin-top, mr: margin-right, ml: margin-left);

@each $key, $item in $margins {
  @for $i from 1 through $size {
    .#{$key}-#{$i} {
        #{$item}: (2em * $i) / 4;
    }
  }
}

$paddings: (pb: padding-bottom, pt: padding-top, pr: padding-right, pl: padding-left);

@each $key, $item in $paddings {
  @for $i from 1 through $size {
    .#{$key}-#{$i} {
        #{$item}: #{$i}px!important;
    }
  }
}