Bootstrap v4 SCSS Media Queries

bootstrap4.scss

$xl-down: "max-width: 9999px";
$lg-down: "max-width: 1199px";
$md-down: "max-width: 991px";
$sm-down: "max-width: 767px";
$xs-down: "max-width: 575px";

$xl-up: "min-width: 1200px";
$lg-up: "min-width: 992px";
$md-up: "min-width: 768px";
$sm-up: "min-width: 576px";
$xs-up: "min-width: 0";

@media ($sm-down) {
  
}