include css with relative URL

Author: philipashlock

Diff for: _includes/header.html

@@ -11,8 +11,8 @@
 
   <title>{{ site.title }}</title>
 
-  <link rel="stylesheet" href="{{ site.root_url }}/assets/css/bootstrap.css">
-  <link rel="stylesheet" href="{{ site.root_url }}/assets/css/site.css">
+  <link rel="stylesheet" href="/assets/css/bootstrap.css">
+  <link rel="stylesheet" href="/assets/css/site.css">
 
   {% capture edit_url %}{{ site.prose_url }}#{{ site.org_name }}/{{ site.repo_name }}/edit/{{ site.branch }}/{{ page.filename }}{% endcapture %}
 </head>