Make TOC pretty. Also put in "[[_TOC_]]" stub for viewing sub-page directly

lib/gollum/frontend/public/gollum/css/template.css

@@ -367,6 +367,35 @@ a.absent {
   margin: 0;
   padding: 0;
 }
+.markdown-body .toc {
+  border: 1px solid #ddd;
+  padding: 5px 10px;
+  margin: 0;
+  border-radius: 3px;
+}
+.markdown-body .toc-title {
+  color: #888;
+  padding: 2px;
+  border-bottom: 1px solid #ddd;
+  margin-bottom: 3px;
+}
+.markdown-body .toc ul {
+  padding-left: 10px;
+  margin: 0;
+}
+.markdown-body .toc>ul {
+  margin-left: 10px;
+  font-size: 17px;
+}
+.markdown-body .toc ul ul {
+  font-size: 15px;
+}
+.markdown-body .toc ul ul ul {
+  font-size: 14px;
+}
+.markdown-body .toc ul li{
+  margin: 0;
+}
 .highlight {
   background: #fff;
 }

lib/gollum/markup.rb

@@ -61,7 +61,7 @@ module Gollum
       doc = Nokogiri::HTML::DocumentFragment.parse(data)
       doc = sanitize.clean_node!(doc) if sanitize
       doc,toc = process_headers(doc)
-      @toc = @sub_page ? @parent_page.toc_data : toc
+      @toc = @sub_page ? ( @parent_page ? @parent_page.toc_data : "[[_TOC_]]" ) : toc
       yield doc if block_given?
       data = doc.to_html
 
@@ -91,9 +91,9 @@ module Gollum
         h.add_child(anchor)
 
         # Build TOC
-        toc ||= Nokogiri::XML::Node.new('ul', doc)
-        tail ||= toc
-        tail_level ||= 1
+        toc ||= Nokogiri::XML::DocumentFragment.parse('<div class="toc"><div class="toc-title">Table of Contents</div></div>')
+        tail ||= toc.child
+        tail_level ||= 0
 
         while tail_level < level
           node = Nokogiri::XML::Node.new('ul', doc)