Centering Block Site Header that contains an image

That works for the logo, but not the actual menu

Not sure if I fully understand.

Can you explain a bit more?

I don't want any space between the logo and the menu

Remove this CSS:

body:not(.home) .main-navigation .navigation-branding {
    margin-right: auto;
}

and try this instead:

body:not(.home) .nav-align-center .inside-navigation {
    justify-content: flex-start;
}

That's perfect!
Thank you for all your help and your patience.
Bruce

Resolved

No problem :)