Build and customize a beautiful advent calendar. You may add a background image to the entire calendar, on each door, and as a background on the content inside each door. You may also add snow- effect and music. Inside each door, you may add a sound, video, text, image, or link. Do note that it is easy for computer-savvy users to reveal the content of all doors right away. If you plan to reveal big secrets on future days you should wait until that day before adding your big secrets to the calendar.