When you previewed the exercises in this book, you probably noticed that course content, words, media, and other objects on a slide, were surrounded by an interface. This is called the Player and it can be as minimal as a 10 pixel border all the way around a course or more elaborate to include logos, menus, and playback controls.
You can make the player transparent by giving the illusion that there is no player at all by adjusting the player colors;
Base border, and
Base slide_bg are set to 100 percent transparent.
What's really great with this feature is that Storyline lets you fully customize how the Player looks ...