$sm-range: calc(40rem - 1px);
$md-range: (40rem, calc(75rem - 1px));
$lg-range: (75rem, calc(90rem - 1px));
$xl-range: (90rem, calc(120rem - 1px));
$xx-range: 120rem;

$md-down: '#{$screen} and (max-width: #{upper-bound($md-range)})';
$lg-down: '#{$screen} and (max-width: #{upper-bound($lg-range)})';
$xl-down: '#{$screen} and (max-width: #{upper-bound($xl-range)})';

$md-up: '#{$screen} and (min-width: #{lower-bound($md-range)})';
$lg-up: '#{$screen} and (min-width: #{lower-bound($lg-range)})';
$xl-up: '#{$screen} and (min-width: #{lower-bound($xl-range)})';

$sm-only: '#{$screen} and (max-width: #{$sm-range})';
$md-only: '#{$screen} and (min-width: #{lower-bound($md-range)}) and (max-width: #{upper-bound($md-range)})';
$lg-only: '#{$screen} and (min-width: #{lower-bound($lg-range)}) and (max-width: #{upper-bound($lg-range)})';
$xl-only: '#{$screen} and (min-width: #{lower-bound($xl-range)}) and (max-width: #{upper-bound($xl-range)})';
$xx-only: '#{$screen} and (min-width: #{$xx-range});