How to keep audio playing while user switch to other browswer tabs?

Jumping in to say this would be more valuable than just music. This would allow me to add a delay to a CONTINUE button when sending the user to an outside resource (such as a website). I want them to NOT be able to click Continue until after a set amount of time, which they should use to navigate the outside resource. Once my set timer completes (using either a slide animation off-screen, or using a layer with its own timeline), the state of my continue button can change... This works—in theory—but as soon as the user clicks the button to launch the outside resource, all timelines pause. I need the option to turn this pause off and continue the timeline clocks.