why my django admin site does not have the css style

After setting up your STATIC_ROOT and STATIC_URL, you may have to run

python manage.py collectstatic

ADMIN_MEDIA_PREFIX is deprecated now, use STATIC_URL instead. Setting STATIC_URL = '/static/' in settings.py should do the job. Try:

import os.path  import sys

PROJECT_ROOT = os.path.normpath(os.path.dirname(__file__))

and then:

STATIC_ROOT = os.path.join(PROJECT_ROOT, 'static')
STATIC_URL = '/static/'

Works on Django 1.4 pre-alpha SVN-16920.

Django does not serve static files on it's own. You have to tell it where the files are.

The ADMIN_MEDIA_PREFIX in the settings.py will point Django in the right location.

Since you're using the development version, you'll want the dev-specific document for static files how-to. Adam's link will lead you to the 1.2 version.