Black bars on the fullscreen (SDL_WINDOW_FULLSCREEN) Windows app

SDL Development
1

Hello,

I am trying to create on MS Windows 11 the full-screen app with the resolution 320x180px.

The notebook screen I am using has widescreen 16:9 aspect ratio, typical for modern monitors, so I expected the complete screen will be filled since the 320x180px has also 16:9 ratio.

Surprisingly I have black bars on the left and right sides of the window, so the image which fills the background is in result horizontally shrank.

There is nothing special about the code, which creates window:

        iWindow = SDL_CreateWindow( APP_TITLE, 
                                    SDL_WINDOWPOS_CENTERED, 
                                    SDL_WINDOWPOS_CENTERED,
                                    320,
                                    180,
                                    SDL_WINDOW_FULLSCREEN );

Here is the photo of the screen:

full_screen_issue
full_screen_issue770×531 348 KB

Can anybody please share a word of advice?

Thanks a lot
STeN