// どこでも font-weight と text-align と color と +top() が書ける設定
=text-block-options($value)
  font-weight: if(font_weight($value), $value, null)
  text-align: if(text_align($value), $value, null)
  color: if(color($value), $value, null)
  white-space: if(white_space($value), $value, null)
  @if px($value)
    +top($value, null)

// +text-block($font-size $line-height $margin-bottom, $font-weight $text-align $color $top)
=text-block($value1: null, $value2: null)
  +rem('font-size', nth($value1, 1))
  +rem('line-height', optional_nth($value1, 2))
  +rem('margin-bottom', optional_nth($value1, 3))
  @if ($value2)
    @for $i from 1 through length($value2)
      +text-block-options(nth($value2, $i))

=letter-spacing-center($space-width: null)
  +rem('letter-spacing', $space-width)
  +rem('text-indent', $space-width)