You can add a fallback value for the font-family by adding another font name separated by a comma. Fallbacks are used in instances where the initial is not found/available.
Add the fallback font serif after the Impact font.
It is great that you solved the challenge, but instead of posting your full working solution, it is best to stay focused on answering the original poster’s question(s) and help guide them with hints and suggestions to solve their own issues with the challenge.
We are trying to cut back on the number of spoiler solutions found on the forum and instead focus on helping other campers with their questions and definitely not posting full working solutions.