Border-box mixin for IE7

ie7-border-box-mixin.scss

/* Thank god no ones uses IE7 anymore, amirite */
@mixin IE7Padding($width: null, $unit: 1px, $paddingLeft: 0, $paddingRight: 0) {
  @if $padding == 0 and $paddingRight != 0 {
    padding-right: $paddingRight * $unit;
    width: $width * $unit;
    .lt-ie8 & {
      padding-right: $paddingRight + $unit;
      width: ($width = $paddingRight) * $unit;
    }
  }
  @else if $paddingRight == 0 and $paddingLeft != 0 {
    padding-left: $paddingLeft; * $unit;
    width: $width * $unit;
    .lt-ie8 & {
      padding-left: $paddingLeft + $unit;
      width: ($width = $paddingLeft) * $unit;
    }
  }
  @else if $paddingRight != 0 and $paddingLeft != 0 {
    padding-right: $paddingRight * $unit;
    padding-left: $paddingLeft * $unit;
    width: $width * $unit;
    .lt-ie8 {
      padding-right: $paddingRight * $unit;
      padding-left: $paddingLeft * $unit;
      width: ($width - $paddingLeft - $paddingRight) * $unit;
     }
  }
}