$screen ?= 'only screen';

// Base Mixin
bp($min, $mq = max-width, $type = $screen)
  if $type != '' and $type != null
    $type = $type + ' and';

  if typeof($min) is string
    $query = '%s' % unquote($min);
  else
    $query = '%s (%s: %s)' % (unquote($type) unquote($mq) $min);

  @media $query
    {block}