Update navbar styling to be closer to mocks

This gets us quite a bit closer to the mocks, though there's still work to be done:

TODO in future PRs:

Highlight links on hover (? - no mocks for this)
Underline the selected page in blue to match mocks (if this is easy using CSS)
Update which pages are linked to (to non-app pages)
- HOME, ABOUT, CONTACT, and FAQ
- bit worried this will be complicated since code assumes they are all app pages right now, but haven't tried to actually change it yet
Remove the account login dropdown (? see discussion points below)
Add search widget to top-bar - Aishah might take this next time
Align navbar links to the right hand side, against the search box (if easy with CSS)

winterstein / sogive-app