What is the purpose of z-index?

Short answer: z-index controls stacking order of overlapping elements.

Example code

.box1 { z-index: 1; } .box2 { z-index: 10; } Higher values appear on top. Key Takeaway: Only works on positioned elements (position ≠ static).

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.