HeadFirst HTML CSS

Hello everyone!
I’ve just finished Chapter 12 of HeadFirst HTML/CSS. Everything is clear except one minor thing.

The selected area goes beyond the navigation bar. How to make the selected area fit exactly the navigation bar? Please, could you help me please?

Have a nice day! Many thanks in advance!

Here’s the screenshot:

Hey and welcome to the forum!

We need to see your code to be able to help you. Also a link to the challenge itself.

Could you please take a look at my CSS code, that stylises the selected area:
Screenshot 2023-03-10 at 05.11.38

Please, can anyone help with this problem?