diff --git a/src/Arts.cs b/src/Arts.cs
index c220170..af7a63f 100644
--- a/src/Arts.cs
+++ b/src/Arts.cs
@@ -87,12 +87,23 @@ static class Arts
         // ground
         meshes["circle"].Draw(
             mat_unlit,
+            Matrix.TRS(
+                V.XYZ(0, 1 * U.cm, 0),
+                Quat.Identity,
+                2.0f
+            ),
+            Color.Hex(0x808080FF).ToLinear()
+        );
+
+        // pool
+        meshes["circle"].Draw(
+            mat_add,
             Matrix.TRS(
                 V.XYZ(0, 0, 0),
                 Quat.Identity,
                 12.0f
             ),
-            Color.Hex(0x808080FF).ToLinear()
+            Color.Hex(0x7090AAFF).ToLinear()
         );
 
         // bamboo