/**
 * Breakpoints
 */
media-down($breakpoint_name)
  @media (max-width: $breakpoints[$breakpoint_name] - $epsilon)
    {block}

media-up($breakpoint_name)
  @media (min-width: $breakpoints[$breakpoint_name])
    {block}

media-between($breakpoint_name_1, $breakpoint_name_2)
  @media (min-width: $breakpoints[$breakpoint_name_1]) and (max-width: $breakpoints[$breakpoint_name_2] - $epsilon)
    {block}