An empty day in a Timeline project can have different states that are represented by colors and icons depending on the content in your Photos app.
- If a date has a dark seaweed color, with no icons or any other colors, it means that there's no videos or photos available for that day in your library. However, you can add content recorded on a different date to it.
- If a date shows a teal/aqua line at the top, it means that there's content for that day in your library.
- A video camera icon means that you have at least one video available for that day.
- A camera icon means there's only photos available for that day.
- Today is represented in a yellow color.