pop-up bar across my header

I had my page laid out nicely, but, suddenly, I notice a green bar pop up across the top of my header when an item was added to the cart. This has a lightbulb and says you have successfully added an item.

First, I would like to get rid of that bar entirely, but there is more. When it first happened, it only stayed a moment, then little cart and checkout text links appeared across my header. That was okay, but now something has pushed my header down and it appears as if it is hanging in mid air, which destroys the look of it. I will attach a screen shot of how it looks now. I don't have one from before it got messed up.

I can't see my attachment, so will try again.