$xs-only: ‘(max-width: #{$screen-xs-max})’;
$sm-up: ‘(min-width: #{$screen-sm-min})’; $sm-down: ‘(max-width: #{$screen-sm-max})’; $sm-only: ‘(min-width: #{$screen-sm-min}) and (max-width: #{$screen-sm-max})’;
$md-up: ‘(min-width: #{$screen-md-min})’; $md-down: ‘(max-width: #{$screen-md-max})’; $md-only: ‘(min-width: #{$screen-md-min}) and (max-width: #{$screen-md-max})’;
$lg-up: ‘(min-width: #{$screen-lg-min})’;