Given that transparency is defaulted to 50% when transparent and your colors otherwise seem to be 50% the brightness, so I theorize that you used an open level with nothing visible (except the black background) and you made your panels bright. It was sufficient enough. It's a wonder what I can do with numbers, isn't it?
"You level up the fastest and easiest if you do things at your own level and no higher or lower" - useful tip
My 2D game - release on Jun 13th; My tutorials