官网解决方案：
https://docs.djangoproject.com/en/1.10/howto/static-files/

我加了：

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)

怎么没效果呢？？
最后开启 debug=True admin css 才行，关闭 debug css 就 404 了