I'm attempting to have a brochure site that gives users an ability to log in to a Zero app from a Login modal. The brochure site is a landing page describing the application and various marketing details. On that page, the desire is to have a Login button that opens a small "Enter user name and password" modal with User name and Password fields. Ideally the app would load in the background while the user is seeing the brochure site and possibly even while the user name and password are entered and being sent to the app.
How can this be accomplished?