web, banner: Add dynamic messages for mobile version

[fstachura]

New design:

[tleb]

Not a fan of the design. Two proposals. First one takes inspiration from your mobile but reduces font size and uses bold. Second one reuses the desktop banner and moves it around. On the second I also reworked the nav links for them to have fluid padding inbetween them. That way they only take a single line, avoiding spending vertical space for nothing. I'll submit that in a separate PR.

I did it in devtools but I could recreate them properly if that works out.