Hello, since I updated my vm from 2.0.26d to 2.6.10 add to cart pop up barely shows. When I check java console, nothing shows as an error creating the issue. Please see image attached also to show you the issue.
I have also tested using with Beez, see attachment for how it looks like too.
[attachment cleanup by admin]
Can only be css - without a live url no one can help you