Site banner overhaul rebase

[yachtcaptain23]

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Tagged reviewers.

Test Plan:

Reviewer Checklist:

Tests

• Adequate test coverage exists to prevent regressions

Security:

• No raw SQL -- Always prefer ActiveRecord query helpers (more info on StackOverflow)
• XSS is mitigated -- Avoid html_safe and raw; escape untrusted content from users and 3rd party APIs (Rails XSS guide and OWASP XSS Prevention Cheat Sheet)