five-for-the-future/themes/pub/wporg/css/tools/_breakpoint.scss

// Kube. CSS & JS Framework
// Copyright (c) 2009-2017, Imperavi LLC.
// License: MIT

@mixin breakpoint($min: 0, $max: 0) {

	$type: type-of($min);

	@if $type == string
	{
		@if $min == sm
		{
			@media (max-width: $sm) { @content; }
		}
		@else if $min == md
		{
			@media (min-width: $sm) and (max-width: $md) { @content; }
		}
		@else if $min == lg
		{
			@media (min-width: $lg) { @content; }
		}
	}
	@else if $type == number
	{
		$query: "all" !default;
		@if $min != 0 and $max != 0 { $query: "(min-width: #{$min}) and (max-width: #{$max})"; }
		@else if $min != 0 and $max == 0 { $query: "(min-width: #{$min})"; }
		@else if $min == 0 and $max != 0 { $query: "(max-width: #{$max})"; }
		@media screen and #{$query} { @content; }
	}
}