Update app.py

app.py

@@ -588,7 +588,8 @@ def server(input, output, session):
         colour_df = pd.DataFrame(data=[col_1_colour,col_2_colour,col_3_colour]).T.values
 
         if colour_df[[0],[2]] == 0:
-            colour_df[colour_df.columns[1]] = 'white'
+            for i in range(len(colour_df)):
+                colour_df[[i][1]] = 'white'
         
         colour_df[[0],[0]] = 'white'
         colour_df[[1],[0]] = 'white'