Background Image size and Header Image size

what should be dimensions of a background image to have it as full-screen size?

what are dimensions of header image size (1600x400 needs to be cropped)

Thank you,

Hello there,

I hope you are doing well today.

The images need to be about 1800x1800px and the theme would create thumbnails to be used for various aspect of the theme.

Best Regards,

Thank you for your help.
1800x1800 does not fill entire screen, I still need to use full-screen settings,
but I will try to work with this dimensions for a time being,

Hey there,

Can you provide me with the URL for your website,
Maybe there’s something I can do with CSS to assist you.

Best Regards,