ROOT = os.path.dirname(os.path.abspath(__file__))
cd = lambda *a: os.path.join(ROOT, *a)
PROJECT = os.path.basename(ROOT)

MEDIA_ROOT = cd('public/uploads')
MEDIA_URL = '/uploads/'
STATIC_ROOT = cd('public/assets')
STATIC_URL = '/assets/'
STATICFILES_FINDERS = (
    'django.contrib.staticfiles.finders.FileSystemFinder',
    'django.contrib.staticfiles.finders.AppDirectoriesFinder',
    'django.contrib.staticfiles.finders.DefaultStorageFinder',
)

<link href="{{ STATIC_URL }}themes/css/bootstrappage.css" rel="stylesheet"/>

{{ STATIC_URL}}

{% load staticfiles %}
<link href="{% static "themes/css/bootstrappage.css" %}" rel="stylesheet"/>