What problem does this address?

There are many settings available to the navigation block which cannot be customized in theme.json. It is beneficial to themes to be able to style blocks via theme.json rather than in block settings, as it means themes can share patterns and simply modify the navigation via theme.json, rather than each theme needing to create its own header to adjust the navigation.

What is your proposed solution?

It is already possible to set colors and typography for the navigation block in theme.json, but the following properties would also be helpful:

• Gap
• Submenu color and background
• Overlay background
• Borders
• Navigation link states (hover, active, focus) (context)
• Hiding more than N items (context)
• Behaviour of dropdowns (context)

This is list is a good starting point but we should anticipate other properties also being needed.

cc @getdave @draganescu