diff --git a/d09/animp.py b/d09/anim.py
similarity index 72%
rename from d09/animp.py
rename to d09/anim.py
index 9f76065..00930e7 100644
--- a/d09/animp.py
+++ b/d09/anim.py
@@ -5,18 +5,23 @@ import time
 class display:
     def __init__(self):
         self.w, self.h = tuple(os.get_terminal_size())
-        #self.h -= 1
         border = "o"
         self.delta = numpy.array((self.w//2, self.h//2))
         top = border * (self.w)
-        line = border + " " * (self.w - 2) + border
-        self.background = top + "".join(
-            line for _ in range(self.h - 2)) + top
+        wodd = self.w%2
+        lines = [
+            border + "░ " * (self.w//2-1) + "░"*wodd + border,
+            border + " ░" * (self.w//2-1) + " "*wodd + border
+        ]
+        self.background = [
+            top + "".join(lines[h%2] for h in range(self.h - 2)) + top,
+            top + "".join(lines[1-h%2] for h in range(self.h - 2)) + top
+        ]
 
     def __call__(self, knots):
         print("\033[0;0H", end='')
         x, y = self.delta + knots[0]
-        J = 20
+        J = 19  # must be odd to see scroll
         if x <= 0:
             self.delta[0] += J
         if x >= self.w-1:
@@ -25,10 +30,10 @@ class display:
             self.delta[1] += J
         if y >= self.h-1:
             self.delta[1] -= J
-        txt = [c for c in self.background]
+        txt = [c for c in self.background[sum(self.delta)%2]]
         for i,knot in enumerate(reversed(knots)):
             x, y = knot + self.delta
-            txt[int(x + y * self.w)] = str(9-i)
+            txt[int(x + y * self.w)] = "\033[30;43m" + str(9-i) + "\033[0m"
         print("".join(txt),end='')
         time.sleep(.008)