I think at the moment it's the same colour as the background. Is there any way to customise it?

Thanks!

currently you can't change the color of the tunnel effect - sorry!

you might be able to make your own version using the custom transition hack in the bitsy hacks repository, but I'm not sure how much work that would be: https://seleb.github.io/bitsy-hacks/

oh ok, thanks so much!

sure thing - good luck!