Navigation: Improve responsive behaviour

[scruffian]

What problem does this address?

There are several aspects of the navigation block that we have added custom CSS for in Blockbase, to overcome some limitations of the block. These are:

• Controlling the alignment and position of items when in overlay mode
• Controlling the size and color of navigation and navigation links when in overlay mode

What is your proposed solution?

I don't have a clear idea of how to solve this. Ideally all of this CSS in Blockbase could be expressed by attributes on the block.

This is what we are trying to achieve:

This is the current behaviour without the additional CSS:

[jasmussen]

Thanks for the ticket! Can you let me know if #36991 at least makes it so it isn't aligned to the bottom?

[getdave]

Closing in favour of #49156