Posted as a benefit to some other future frustrated Googler.

The problem: style sheets break when called from any directory other than home.

The solution: open /js/init.js and make the following corrections/changes:

1: add an empty YAML block at the top

- - -

#Empty YAML block here to trigger processing

- - -

2: add a site.url reference to the prefix code in the skel.init function (or site.baseurl, depending on how your _config.yml is set up)

skel.init(
	[...]
		prefix: '  { { site.url } } /css/style',
	[...] )

That’s it.

(credit where credit’s due: @techieshark’s jekyll adaptation of the Strongly Typed theme gave me the answer. And @n33co for creating the theme in the first place.)