@medium-and-up: ~"only screen and (min-width : @{small-screen-up})";
@large-and-up: ~"only screen and (min-width : @{medium-screen-up})";
@extra-large-and-up: ~"only screen and (min-width : @{large-screen-up})";
@small-and-down: ~"only screen and (max-width : @{small-screen})";
@medium-and-down: ~"only screen and (max-width : @{medium-screen})";
@medium-only: ~"only screen and (min-width : @{small-screen-up}) and (max-width : @{medium-screen})";