The problem is setting the static file.

I set the file according to the official document said.

I first created a directory called `static` in the app which my URL links to

Then I made some changes on the template.

The code is below:

```
#Structure
src
|---makesite
|---sitemaker(app)
|---templates
|        |----main.html                 
|        |----static
|                |-css
|                   |-style.css 
|-static
|-manage.py

#The settings.py
STATIC_URL = '/static/'
STATIC_URL = '/static/'
STATICFILES_DIRS = [
os.path.join(BASE_DIR, "static"),]
STATIC_ROOT = os.path.join(BASE_DIR,"templates/static")

#The urls.py
from django.conf.urls import url
from django.contrib import admin
from makesite.views import make_site
from django.conf import settings
from django.conf.urls.static import static
urlpatterns = [
    url(r'^admin/', admin.site.urls),
    url(r'^main/',make_site),
]
if settings.DEBUG:
    urlpatterns += static(settings.STATIC_URL, documents_root=settings.STATIC_ROOT)

#The File structure

#The template
<!DOCTYPE html>
{% load staticfiles %}
<html>
<head>
<title>Main Site</title>
<link rel='stylesheet prefetch' href='https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css'>
<link rel= "{% static %}'css/style.css'" href="style.css">

```