Really cool stuff, ehmorris. Your work harkens back to the early days of the web when bundlers and minifiers were the exception, rather than the rule. Work like this can really help beginners understand how powerful vanilla JavaScript can be by just looking at your source!
One neat thing you can do is embed an SVG favicon in your html page, which will be properly rendered at all resolutions on all major browsers - plus it saves another sub-resource request. Here is the favicon at https://simpatico.io/svg
<link id="favicon" rel="icon" type="image/svg+xml" href="data:image/svg+xml,
<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 1 1'>
<rect width='1' height='1' fill='DodgerBlue' />
</svg>"/>
This can help you make your already clean source even cleaner and delete some subresources. Cheers!