Makefile improvements

Makefile

@@ -2,25 +2,28 @@
 temp_sed_file:=$(shell mktemp).sed
 temp_svg_file:=$(shell mktemp).svg
 ifdef dark
-	dark_color=$(dark)
+	ifneq ($(wildcard $(dark)),)
+		dark_mime:=$(shell file -bN --mime-type $(dark))
+		dark_color?=transparent
+	else
+		dark_color:=$(dark)
+	endif
 endif
 ifdef light
-	light_color=$(light)
+	ifneq ($(wildcard $(light)),)
+		light_mime:=$(shell file -bN --mime-type $(light))
+		light_color?=transparent
+	else
+		light_color:=$(light)
+	endif
 endif
 ifdef middle
-	middle_color=$(middle)
-endif
-ifneq ($(wildcard $(dark)),)
-  dark_mime=$(shell file -bN --mime-type $(dark))
-	dark_color=transparent
-endif
-ifneq ($(wildcard $(light)),)
-  light_mime=$(shell file -bN --mime-type $(light))
-	light_color=transparent
-endif
-ifneq ($(wildcard $(middle)),)
-  middle_mime=$(shell file -bN --mime-type $(middle))
-	middle_color=transparent
+	ifneq ($(wildcard $(middle)),)
+		middle_mime:=$(shell file -bN --mime-type $(middle))
+		middle_color?=transparent
+	else
+		middle_color:=$(middle)
+	endif
 endif
 size?=1024
 dark_color?=black

logo.svg

@@ -40,7 +40,7 @@
       <rect width="100%" height="50%" fill="url(#layer-1-gradient)" />
     </mask>
     <mask id="layer-1-alt-gradient-mask">
-      <rect width="100%" height="100%" fill="url(#layer-1-gradient)" transform="translate(512 0) scale(-1 1) rotate(-90 256 256)" />
+      <rect width="100%" height="100%" fill="white" mask="url(#layer-1-gradient-mask)" transform="translate(512 0) scale(-1 1) rotate(-90 256 256)" />
     </mask>
     <mask id="layer-1-mask">
       <rect x="46%" width="8%" height="50%" fill="white" />