diff --git a/README.org b/README.org
index 3e57e92..fcbba92 100644
--- a/README.org
+++ b/README.org
@@ -4,6 +4,9 @@ Unicode plotting library for [[https://cons.io/][Gerbil Scheme]].
 
 Depends on [[https://github.com/dlozeve/fancy][Fancy]] for colors and display.
 
+#+ATTR_HTML: :width 100% :style margin-left: auto; margin-right: auto;
+[[./demo.png]]
+
 ** Features
 
 - Braille canvas for plotting
diff --git a/demo.png b/demo.png
new file mode 100644
index 0000000..db79963
Binary files /dev/null and b/demo.png differ
diff --git a/demo.ss b/demo.ss
index 3a32cc5..b159bb2 100755
--- a/demo.ss
+++ b/demo.ss
@@ -9,5 +9,6 @@
 (def (main . args)
   (let* ((xs (iota 1000 0 0.01))
 	 (ys1 (map cos xs))
-	 (ys2 (map sin xs)))
-    (displayln (line-plot [xs ys1 ys2]))))
+	 (ys2 (map (lambda (x) (/ 1 (+ 0.5 x))) xs))
+	 (ys3 (map (lambda (x) (sin (* 2 x))) xs)))
+    (displayln (line-plot [xs ys1 ys2 ys3]))))
diff --git a/uniplot/braille.ss b/uniplot/braille.ss
index b13c2a4..a095bf5 100644
--- a/uniplot/braille.ss
+++ b/uniplot/braille.ss
@@ -44,7 +44,7 @@
 (def (indexf pred . lsts)
   (find pred (apply map list lsts)))
 
-(def (canvases->string canvases (colors '(red green cyan yellow magenta white)))
+(def (canvases->string canvases colors)
   (def canvases-str (map canvas->string canvases))
   (def size (string-length (car canvases-str)))
   (apply str
diff --git a/uniplot/lineplot.ss b/uniplot/lineplot.ss
index ece0da4..80e0099 100644
--- a/uniplot/lineplot.ss
+++ b/uniplot/lineplot.ss
@@ -6,6 +6,8 @@
 	:dlozeve/uniplot/braille
 	:dlozeve/fancy/format)
 
+(def +default-colors+ '(green blue red yellow cyan magenta white))
+
 (def (scale-fn lo hi)
   (lambda (x) (/ (- x lo) (- hi lo))))
 
@@ -18,20 +20,18 @@
 			 #t))
   canvas)
 
-(def (line-plot lsts width: (width 160) height: (height 80))
-  (match lsts
-    ([ys] (canvas->string
-	   (draw-canvas (iota (length ys)) ys
-			(scale-fn 0 (length ys))
-			(scale-fn (apply min ys) (apply max ys))
-			width: width height: height)))
-    ([xs ys] (canvas->string
-	      (draw-canvas xs ys
-			   (scale-fn (apply min xs) (apply max xs))
-			   (scale-fn (apply min ys) (apply max ys))
-			   width: width height: height)))
-    ([xs . yss]
-     (canvases->string
+(def (line-plot lsts (colors +default-colors+) width: (width 160) height: (height 80))
+  (canvases->string
+   (match lsts
+     ([ys] [(draw-canvas (iota (length ys)) ys
+			 (scale-fn 0 (length ys))
+			 (scale-fn (apply min ys) (apply max ys))
+			 width: width height: height)])
+     ([xs ys] [(draw-canvas xs ys
+			    (scale-fn (apply min xs) (apply max xs))
+			    (scale-fn (apply min ys) (apply max ys))
+			    width: width height: height)])
+     ([xs . yss]
       (let* ((x-scale-fn (scale-fn (apply min xs) (apply max xs)))
 	     (all-ys (flatten yss))
 	     (min-ys (apply min all-ys))
@@ -39,4 +39,5 @@
 	     (y-scale-fn (scale-fn min-ys max-ys)))
 	(for/collect ((ys yss))
 	  (draw-canvas xs ys x-scale-fn y-scale-fn
-		       width: width height: height)))))))
+		       width: width height: height)))))
+   colors))