Apply rebranding

[kprosise]

Color scheme, font, and logo have been updated.

QA: Checked rendered output, output appears to be correct visually, and no issues building.

This commit applies to issue FFTK-3775, "Rebranding…"

PR Template and Checklist

Please complete as much as possible to speed up the reviewing process.

Readiness and adding reviewers as appropriate is required.

All PRs should be reviewed by a technical writer/documentation team and a peer.
If effecting customers—which is a majority of content changes—a member of Customer Success must also review.

Readiness

• Merge (pending reviews)
• Merge after date or event
• Draft

Overview

Why merge this PR? What does it solve?

Checklist

• Avoid changing any header associated with a link/reference.
• View HTML in a browser to check rendering.
• follow best practices for commits.
  • Descriptive title written in the imperative.
  • Include brief overview of QA steps taken.
  • Mention any related issues numbers.
  • End message with sign off/DCO line (-s, --signoff).
  • Sign commit with your gpg key (-S, --gpg-sign).
  • Squash commits if needed.
• Request PR review by a technical writer and at least one peer.