convex/concave/zoom)
        backgroundTransition: 'none',

        // Number of slides away from the current that are visible
        viewDistance: 3,

        // Number of slides away from the current that are visible on mobile
        // devices. It is advisable to set this to a lower number than
        // viewDistance in order to save resources.
        mobileViewDistance: 2,

        // The "normal" size of the presentation, aspect ratio will be preserved
        // when the presentation is scaled to 