Currently INCLUDECSS and INCLUDEJS default to searching inside style/template/... for files.

CSS files are not inside the template folder, they are in "theme" folders. So INCLUDECSS can not work at this time.

Perhaps the strategy would be to default INCLUDEJS to template folders, and INCLUDECSS to theme folders.

But Extensions must also be considered. Maybe for extensions (namespaced) we should not go deep into template or theme folders by default, and require the authors to use template/ or theme/ in their include tags.

Ideally, we should be able to do stuff like this:

CORE:
<!-- INCLUDEJS file.js --> to find: styles/(style match)/template/file.js

<!-- INCLUDECSS file.css --> to find: styles/(style match)/theme/file.css

Extensions:
<!-- INCLUDEJS @foo_bar/template/file.js --> to find: ext/foo/bar/styles/(style match)/template/file.js

<!-- INCLUDECSS @foo_bar/theme/file.css --> to find: ext/foo/bar/styles/(style match)/theme/file.css

and that would also allow for this:
<!-- INCLUDEJS @foo_bar/assets/plugin.js --> to find: ext/foo/bar/styles/(style match)/assets/plugin.js