fix url for custom.css

served from .jupyter/custom

notebook/templates/page.html

@@ -13,7 +13,7 @@
     {% block stylesheet %}
     <link rel="stylesheet" href="{{ static_url("style/style.min.css") }}" type="text/css"/>
     {% endblock %}
-    <link rel="stylesheet" href="{{ static_url("custom/custom.css") }}" type="text/css" />
+    <link rel="stylesheet" href="{{ base_url }}custom/custom.css" type="text/css" />
     <script src="{{static_url("components/es6-promise/promise.min.js")}}" type="text/javascript" charset="utf-8"></script>
     <script src="{{static_url("components/requirejs/require.js") }}" type="text/javascript" charset="utf-8"></script>
     <script>