diff --git a/IPython/frontend/html/notebook/static/css/notebook.css b/IPython/frontend/html/notebook/static/css/notebook.less
similarity index 100%
rename from IPython/frontend/html/notebook/static/css/notebook.css
rename to IPython/frontend/html/notebook/static/css/notebook.less
diff --git a/IPython/frontend/html/notebook/static/css/renderedhtml.css b/IPython/frontend/html/notebook/static/css/renderedhtml.less
similarity index 100%
rename from IPython/frontend/html/notebook/static/css/renderedhtml.css
rename to IPython/frontend/html/notebook/static/css/renderedhtml.less
diff --git a/IPython/frontend/html/notebook/static/css/tooltip.css b/IPython/frontend/html/notebook/static/css/tooltip.less
similarity index 100%
rename from IPython/frontend/html/notebook/static/css/tooltip.css
rename to IPython/frontend/html/notebook/static/css/tooltip.less
diff --git a/IPython/frontend/html/notebook/templates/notebook.html b/IPython/frontend/html/notebook/templates/notebook.html
index 8b6514fdd..dd458628d 100644
--- a/IPython/frontend/html/notebook/templates/notebook.html
+++ b/IPython/frontend/html/notebook/templates/notebook.html
@@ -16,12 +16,12 @@ window.mathjax_url = "{{mathjax_url}}";
 
 <link rel="stylesheet" href="{{ static_url("prettify/prettify.css") }}"/>
 
-<link rel="stylesheet" href="{{ static_url("css/notebook.css") }}" type="text/css" />
 <link rel="stylesheet" href="{{ static_url("css/celltoolbar.css") }}" type="text/css" />
-<link rel="stylesheet" href="{{ static_url("css/tooltip.css") }}" type="text/css" />
-<link rel="stylesheet" href="{{ static_url("css/renderedhtml.css") }}" type="text/css" />
+<link rel="stylesheet/less" href="{{ static_url("css/notebook.less") }}" type="text/css" />
+<link rel="stylesheet/less" href="{{ static_url("css/tooltip.less") }}" type="text/css" />
+<link rel="stylesheet/less" href="{{ static_url("css/renderedhtml.less") }}" type="text/css" />
 
-<link rel="stylesheet" href="{{ static_url("css/printnotebook.css") }}" type="text/css" media="print"/>
+<link rel="stylesheet/less" href="{{ static_url("css/printnotebook.less") }}" type="text/css" media="print"/>
 {% endblock %}
 
 {% block params %}
@@ -182,6 +182,7 @@ data-notebook-id={{notebook_id}}
 
 {% block script %}
 
+<script src="{{ static_url("js/less/less-1.3.1.min.js") }}" charset="utf-8"></script>
 <script src="{{ static_url("codemirror/lib/codemirror.js") }}" charset="utf-8"></script>
 <script src="{{ static_url("codemirror/lib/util/loadmode.js") }}" charset="utf-8"></script>
 <script src="{{ static_url("codemirror/lib/util/multiplex.js") }}" charset="utf-8"></script>