I have followed all of the documentation for building a custom module, it all seems pretty straight forward. However, I seem to be missing a couple of small things.
Two issues:
No CSS rules placed in my-plugin/my-module/css/frontend.css (example file path) are not being found, or even loaded. However if they are placed in my-plugin/my-module/includes/frontend.php under a style tag they work fine.
Same is happening with javascript placed within frontend.js.php. Basically everything front end related has to be placed within the frontend.php file, and no other files get referenced.
What am I missing here?