diff --git a/knob.py b/knob.py
index 3561854..4145033 100644
--- a/knob.py
+++ b/knob.py
@@ -3,7 +3,7 @@
 import math
 
 from nanogui import Color, Cursor, FloatBox, Vector2f, Vector2i, Widget, glfw
-from nanogui.nanovg import BUTT, RGB, RGBA, RGBAf, LerpRGBA, NVGwinding, RGBAf
+from nanogui.nanovg import BUTT, LerpRGBA, NVGwinding, RGB, RGBA, RGBAf
 
 
 class Knob(Widget):
diff --git a/nanogui_customwidget.py b/nanogui_customwidget.py
index 8342ef9..a4787e8 100644
--- a/nanogui_customwidget.py
+++ b/nanogui_customwidget.py
@@ -3,14 +3,14 @@
 import nanogui
 from nanogui import glfw
 from nanogui import BoxLayout, Color, Label, Orientation, Screen, Widget, Window, Vector2i
-from nanogui.nanovg import RGBAf, RGB
+from nanogui.nanovg import LerpRGBA, RGBAf, RGB
 
 
 class CustomWidget(Widget):
     def __init__(self, parent, size=(100, 100), color=Color(192, 0, 0, 255)):
         super().__init__(parent)
         self._size = size
-        self._color = RGBAf(color.r, color.g, color.b, color.w)
+        self.color = RGBAf(color.r, color.g, color.b, color.w)
 
     def preferred_size(self, ctx):
         return Vector2i(self._size)
@@ -21,13 +21,18 @@ class CustomWidget(Widget):
 
         ctx.BeginPath()
         ctx.Rect(pos[0], pos[1], size[0], size[1])
-        ctx.FillColor(RGB(128, 128, 0))
+        bg = LerpRGBA(RGB(64, 64, 64), self.color, 0.3)
+        ctx.FillColor(bg)
         ctx.Fill()
         ctx.BeginPath()
         ctx.StrokeWidth(5.0)
-        ctx.StrokeColor(self._color)
-        ctx.MoveTo(pos[0], pos[1])
-        ctx.LineTo(pos[0] + size[0], pos[1] + size[1] / 3.0)
+        ctx.StrokeColor(self.color)
+        ctx.Rect(
+            pos[0] + size[0] / 4.0,
+            pos[1] + size[1] / 4.0,
+            size[0] / 2.0,
+            size[1] / 2.0,
+        )
         ctx.Stroke()
         ctx.ClosePath()
 
@@ -42,7 +47,7 @@ class CustomWidgetApp(Screen):
 
         Label(self.win, "NanoGUI CustomWidget Demo", "sans-bold")
 
-        cw = CustomWidget(self.win, (200, 100))
+        _ = CustomWidget(self.win, (200, 100))
 
         self.draw_all()
         self.set_visible(True)