1 files changed, 25 insertions, 4 deletions
diff --git a/lib/rdoc/generator/template/darkfish/_sidebar_table_of_contents.rhtml b/lib/rdoc/generator/template/darkfish/_sidebar_table_of_contents.rhtml
index bf70819f64..b1e047b5f7 100644
--- a/lib/rdoc/generator/template/darkfish/_sidebar_table_of_contents.rhtml
+++ b/lib/rdoc/generator/template/darkfish/_sidebar_table_of_contents.rhtml
@@ -3,16 +3,37 @@
              else
                current.comment
              end
-   table = current.parse(comment).table_of_contents
+   table = current.parse(comment).table_of_contents.dup
 
    if table.length > 1 then %>
 <div class="nav-section">
   <h3>Table of Contents</h3>
 
+    <%- display_link = proc do |heading| -%>
+      <a href="#<%= heading.label current %>"><%= heading.plain_html %></a>
+    <%- end -%>
+
+    <%- list_siblings = proc do -%>
+      <%- level = table.first&.level -%>
+      <%- while table.first && table.first.level >= level -%>
+        <%- heading = table.shift -%>
+        <%- if table.first.nil? || table.first.level <= heading.level -%>
+          <li><% display_link.call heading -%>
+        <%- else -%>
+          <li>
+            <details open>
+              <summary><%- display_link.call heading -%></summary>
+              <ul class="link-list" role="directory">
+                <% list_siblings.call %>
+              </ul>
+            </details>
+          </li>
+        <%- end -%>
+      <%- end -%>
+    <%- end -%>
+
   <ul class="link-list" role="directory">
-<%-   table.each do |heading| -%>
-    <li><a href="#<%= heading.label current %>"><%= heading.plain_html %></a>
-<%-   end -%>
+    <% list_siblings.call %>
   </ul>
 </div>
 <%- end -%>