$vertical_align_baseline:   baseline !default;
$vertical_align_sub:         sub !default;
$vertical_align_super:       super !default;
$vertical_align_text_top:    text-top !default; 
$vertical_align_text_bottom: text-bottom !default;
$vertical_align_middle:      middle !default;
$vertical_align_top:         top !default;
$vertical_align_bottom:      bottom !default;
$vertical_align: (
  baseline:         $vertical_align_baseline,
  sub:              $vertical_align_sub,
  super:            $vertical_align_super,
  text_top:         $vertical_align_text_top,
  text_bottom:      $vertical_align_text_bottom,
  middle:           $vertical_align_middle,
  top:              $vertical_align_top,
  bottom:           $vertical_align_bottom
);