mixins.scss

@mixin cq-prolyfill($query) {
	&#{cq-prolyfill($query)} {
		@content;
	}
}

@function cq-prolyfill($query) {
	@return unquote(".\\:container\\(" + cq-prolyfill-escape(cq-prolyfill-strip-spaces(to-lower-case($query))) + "\\)");
}

@function cq-prolyfill-add-backslash($string, $search) {
	$index: str-index($string, $search);
	@while $index {
		$string: str-insert($string, '\\', $index);
		$newIndex: if(
			str-length($string) < $index + 2,
			null,
			str-index(str-slice($string, $index + 2), $search)
		);
		$index: if($newIndex, $index + 1 + $newIndex, null);
	}
	@return $string;
}

@function cq-prolyfill-remove($string, $search) {
	$index: str-index($string, $search);
	@while $index {
		$string: str-slice($string, 1, $index - 1) + str-slice($string, $index + 1);
		$index: str-index($string, $search);
	}
	@return $string;
}

@function cq-prolyfill-escape($string) {
	@each $char in '[' ']' '!' '"' '#' '$' '%' '&' "'" '(' ')' '*' '+' ',' '.' '/' ':' ';' '<' '=' '>' '?' '@' '^' '`' '{' '|' '}' '~' {
		$string: cq-prolyfill-add-backslash($string, $char);
	}
	@return $string;
}

@function cq-prolyfill-strip-spaces($string) {
	// tab, line feed, carriage return and space
	$chars: "\9\a\d\20";
	@for $i from 1 through str-length($chars) {
		$string: cq-prolyfill-remove(
			$string,
			str-slice($chars, $i, $i)
		);
	}
	@return $string;
}