custom.css etc no longer supported in page.html template?

[psychemedia]

The page.html template using to include loading of custom.css from .jupyter/custom path with a line of the form:

<link rel="stylesheet" href="{{ base_url }}custom/custom.css" type="text/css" />

This meant custom styles could be used to support custom branding of pages such as the login.html page, which inherits from page.html.

It seems as if the custom styling is no longer loaded into the page.html template. Is there a particular reason why?