Improve branding of single page HTML documents

An easy entry point to Quarto for a lot of people is stand-alone HTML pages (as opposed to HTML pages in a website).
These currently get minimal impact from brand particularly for brands with black text on white backgrounds.

Example

_brand.yml

color:
  primary: "#447099"
logo:
  small: Posit-Logos-2024_horiz-white.svg

A standalone HTML page:

---
title: Standalone document
author: Charlotte Wickham
---

## Introduction

<http://quarto.org>

{{< lipsum  1 >}}

Current treatment:

Suggestions

One approach might be to fake a "navbar" just to add a band of color and logo. E.g. equivalent to adding _quarto.yml:

project: 
  type: website

website:
  search: false
  navbar: 
    pinned: true

Reproduce the standalone HTML example with _brand.yml, then compare its branding with the suggested _quarto.yml website/navbar treatment. Start from the standalone HTML rendering entry point in the Quarto CLI; done means standalone pages visibly apply the configured brand color and logo without requiring a website project.