CSS not loading wrong MIME type Django

Adding following snippet into settings.py file may fix your problem:

import mimetypes
mimetypes.add_type("text/css", ".css", True)

This particular behaviour varies between the development(DEBUG=True) and deployment environment(DEBUG=False).

So if you are developing locally with DEBUG=False there is a high chance of this error. But once deployed on any server it will work without any error. If you want to avoid this error during development set DEBUG=True

I ran into this issue during development (production was using Nginx and serving from /static_cdn folder without any issues).

The solution came from the Django docs: https://docs.djangoproject.com/en/3.1/howto/static-files/#serving-static-files-during-development

from django.conf import settings
from django.conf.urls.static import static

urlpatterns = [
    # ... the rest of your URLconf goes here ...
] + static(settings.STATIC_URL, document_root=settings.STATIC_ROOT)