[CMS] Create general style for the admin interface

[tudoramariei]

The Django admin interface should be implemented so that it looks according to the specifications

UX Specs Link: https://www.figma.com/file/qOyFrU8T6LXnJw7YcoVW85/Seismic-Risk?node-id=586%3A0

[aramboi]

From past experience, customizing and maintaining a custom Django admin interface requires a lot of time, effort and intimate Django admin knowledge as not all things you can customize are documented in the official docs.

I would advise leaving the Django admin as is, mostly because it will not be used by the end user primarily, but just by admins and staff members. Although not ideal (the mobile version is lacking), it is functional enough for a small project like this one.

At the moment we have jet installed as an admin skin, but this is not maintained any more. It has transitioned to a service that is hosted on https://www.jetadmin.io/ and interfaces with their library that basically transforms the admin into an api that their hosted interface talks to. So if they go out of business, so does the projects admin interface. :/

The only Django admin customization project that has been constantly updated and maintained over the years, that I know of, is https://github.com/sehmaschine/django-grappelli and I think the reason that is, is because it does not try to do too much.

[tudoramariei]

Closing as per @aramboi's comment