Mobile First | Shouldn't use fetch for data.json

Hello!

I finished my project and found a lot of fun and experience from it.

Only 3 questions appeared:

1. Is it OK to use fetch to get data from JSON file?

I met lot of errors which repaired on their own through the night. Found the solution to use import instead.

2. Is the way I segregate CSS OK?

3. How to make my page load faster? When you switch between sections it loads long at first, then loaded once, loads fast. Why?

Thanks for feedback!