mobileFirst = true;

sm-size = 568px;
md-size = 768px;
lg-size = 1024px;
xl-size = 1280px;

if mobileFirst
  sm-size = sm-size + 1;
  md-size = md-size + 1;
  lg-size = lg-size + 1;
  xl-size = xl-size + 1;
  first = 'min';
else
  sm-size = sm-size - 1;
  md-size = md-size - 1;
  lg-size = lg-size - 1;
  xl-size = xl-size - 1;
  first = 'max';

sm()
  @media ({first}-width: sm-size)
    {block}
  
md()
  @media ({first}-width: md-size)
    {block}

lg()
  @media ({first}-width: lg-size)
    {block}

xl()
  @media ({first}-width: xl-size)
    {block}

portrait()
  @media (orientation: portrait)
    {block}

landscape()
  @media (orientation: landscape)
    {block}