Step 3: Layer Content and Backgrounds
What you'll learn: How to use mode="contain" for parallel layers and mode="fit" for backgrounds.
Live
Contain Item 1 (5s)
Contain Item 2 (8s — sets total)
Fit Background (spans full 8s)
Try it yourself: Notice how Item 2 (8s) determines the total duration, and the fit element spans it automatically.