From cc3a8668f2f6b75b0a4ea5d13b08b718fca49cd3 Mon Sep 17 00:00:00 2001
From: Thomas Kluyver <thomas@kluyver.me.uk>
Date: Fri, 15 Apr 2016 21:49:32 +0100
Subject: [PATCH] Override mimetype for .css files

This should avoid the issue several people have had with unstyled pages
on misconfigured Windows systems. I think practicality beats purity
here.

Closes gh-1350
---
 notebook/notebookapp.py | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/notebook/notebookapp.py b/notebook/notebookapp.py
index 0325670e5..a2b4ee7c6 100644
--- a/notebook/notebookapp.py
+++ b/notebook/notebookapp.py
@@ -12,6 +12,7 @@ import importlib
 import io
 import json
 import logging
+import mimetypes
 import os
 import random
 import re
@@ -1115,7 +1116,14 @@ class NotebookApp(JupyterApp):
                         raise
                     self.log.warning("Error loading server extension %s", modulename,
                                   exc_info=True)
-    
+
+    def init_mime_overrides(self):
+        # On some Windows machines, an application has registered an incorrect
+        # mimetype for CSS in the registry. Tornado uses this when serving
+        # .css files, causing browsers to reject the stylesheet. We know the
+        # mimetype always needs to be text/css, so we override it here.
+        mimetypes.add_type('text/css', '.css')
+
     @catch_config_error
     def initialize(self, argv=None):
         super(NotebookApp, self).initialize(argv)
@@ -1128,6 +1136,7 @@ class NotebookApp(JupyterApp):
         self.init_terminals()
         self.init_signal()
         self.init_server_extensions()
+        self.init_mime_overrides()
 
     def cleanup_kernels(self):
         """Shutdown all kernels.