@each $name, $size in $sizes {

  /* margin-top */
  .#{$prefix}m#{$delimiter1}t#{if($name != '', $delimiter2 + $name, '')} {
    margin-top: #{$size} !important;
  }
  /* margin-right */
  .#{$prefix}m#{$delimiter1}r#{if($name != '', $delimiter2 + $name, '')} {
    margin-right: #{$size} !important;
  }
  /* margin-bottom */
  .#{$prefix}m#{$delimiter1}b#{if($name != '', $delimiter2 + $name, '')} {
    margin-bottom: #{$size} !important;
  }
  /* margin-left */
  .#{$prefix}m#{$delimiter1}l#{if($name != '', $delimiter2 + $name, '')} {
    margin-left: #{$size} !important;
  }

  /* horizontal margins */
  .#{$prefix}m#{$delimiter1}#{$h}#{if($name != '', $delimiter2 + $name, '')} {
    margin-left: #{$size} !important;
    margin-right: #{$size} !important;
  }
  /* vertical margins */
  .#{$prefix}m#{$delimiter1}#{$v}#{if($name != '', $delimiter2 + $name, '')} {
    margin-top: #{$size} !important;
    margin-bottom: #{$size} !important;
  }
  /* all margins */
  .#{$prefix}m#{$delimiter1}#{$a}#{if($name != '', $delimiter2 + $name, '')} {
    margin: #{$size} !important;
  }
}

/* NEGATIVE MARGINS */
@each $name, $size in $sizes {

  $negName: $neg + $name;

  // DON'T run, if it is 'auto'
  // (because '-auto;' is not a valid value)

  @if $size != auto {
  @if $size != 0 {

    /* margin-top */
    .#{$prefix}m#{$delimiter1}t#{if($name != '', $neg + $delimiter2 + $name, $neg)} {
      margin-top: -#{$size} !important;
    }
    /* margin-right */
    .#{$prefix}m#{$delimiter1}r#{if($name != '', $neg + $delimiter2 + $name, $neg)} {
      margin-right: -#{$size} !important;
    }
    /* margin-bottom */
    .#{$prefix}m#{$delimiter1}b#{if($name != '', $neg + $delimiter2 + $name, $neg)} {
      margin-bottom: -#{$size} !important;
    }
    /* margin-left */
    .#{$prefix}m#{$delimiter1}l#{if($name != '', $neg + $delimiter2 + $name, $neg)} {
      margin-left: -#{$size} !important;
    }

    /* horizontal margins */
    .#{$prefix}m#{$delimiter1}#{$h}#{if($name != '', $neg + $delimiter2 + $name, $neg)} {
      margin-left: -#{$size} !important;
      margin-right: -#{$size} !important;
    }
    /* vertical margins */
    .#{$prefix}m#{$delimiter1}#{$v}#{if($name != '', $neg + $delimiter2 + $name, $neg)} {
      margin-top: -#{$size} !important;
      margin-bottom: -#{$size} !important;
    }
    /* all margins */
    .#{$prefix}m#{$delimiter1}#{$a}#{if($name != '', $neg + $delimiter2 + $name, $neg)} {
      margin: -#{$size} !important;
    }

  } // end @if
  } // end 2nd @if
}