ALT Screenshot of code and result. The first example has --a: 50% and --b: 70%. The width formula gives us 20%. The min-width formula gives us -20% and is ignored, defaulting to 0.Computed width is 20% of the parent's width. The second example has --a: 80% and --b: 30%. The width formula gives us -50% and is ignored, defaulting to 0. The min-width formula gives us 50%. Computed width is 50% of the parent's width.

ALT const book = { 'title': 'Harry Potter', 'price': { 'retail': 15, 'sale': 10 } }; // optional chaining (?) // concise property accesses with built-in nullish checking salePrice = book?.price?.sale; // nullish coalescing (??) // replaces logical OR || when setting default values genre = book?.genre ?? 'Unknown'