Media mixin: support arbitrary units

Author: JirkaVebr

src/styles/mixins/media.sass

@@ -19,11 +19,15 @@
 		+media(123M)
 		// @media (max-width: 456px)
 
+		+media(123em 456Mem)
+		// @media (min-width: 123em) and (max-width: 456em)
+
 		+media($break480 '(screen)', 300 500M, $landscape)
 		// @media (min-width: 480px) and (screen), (min-width: 300px) and (max-width: 500px), (orientation: landscape)
 
 
 =media($breakpoints...)
+	$MAX: 'M'
 	$media: ''
 	$disjunctionCount: length($breakpoints)
 
@@ -35,7 +39,18 @@
 			$literal: nth($conjunction, $j)
 
 			@if type-of($literal) == number
-				$literal: '(#{if(unit($literal) == 'M', 'max', 'min')}-width: #{$literal / ($literal * 0 + 1)}px)'
+				$literalUnit: unit($literal)
+				$maxMode: str-slice($literalUnit, 0, str-length($MAX)) == $MAX
+				$extremum: 'min'
+
+				@if $maxMode
+					$extremum: 'max'
+					$literalUnit: str-slice($literalUnit, str-length($MAX) + 1)
+
+				@if $literalUnit == ''
+					$literalUnit: 'px'
+
+				$literal: '(#{$extremum}-width: #{$literal / ($literal * 0 + 1)}#{$literalUnit})'
 
 			$media: $media + $literal + if($j == $conjunctionCount, '', ' and ')