The site describes the popup as an "overlay." Another commenter used the words "div popup." I'm writing this on a machine with Chromium and Firefox on a nearl

The site describes the popup as an "overlay." Another commenter used the words "div popup." I'm writing this on a machine with Chromium and Firefox on a nearly new Linux Mint 14 install (all packages are up-to-date) with no browser extensions or other weirdness. When I click the "Pay with Card" button in the article, both browsers open it in a new tab. Are my browsers broken, is Stripe's code broken, or is there some miscommunication about what the button is supposed to do?