Minor, properly substituted removed define.

includes/colors.c

@@ -139,7 +139,7 @@ static void b(char * const str) {
     while (token) {
         c = token[0];
         if (isdigit(c)) {
-            decspan(c - ASCII_ZERO);
+            decspan(c - '0');
             if (strlen(token) > 1) {
                 printf("%s", token + 1);
             }