I am currently developing a website that will cater for a community of medical students. As the topics discussed on the site will be of a sensitive nature, I want to restrict user registration so that it only allows e-mail addresses of our university. Basically, I need to block all e-mail addresses apart from @university.ac.uk. I've searched for what kind of string I should put in the 'Block' field of Access Control but have failed miserably.
> Maybe leave that to theme? Let theme decide if it wants to use
> drupal.css or not. A hook_theme_css() or something. This way, if site is
> configured to allow users to change themes, some themes can use
> drupal.css and some can choose not to use it.
This is already possible. A theme can override any CSS file that was added
with the correct Drupal APIs. In core all css is added this way.