Conditionally adding toggle sidebar button if there are sidebars to show

Author: max-marped

src/sphinx_book_theme/theme/sphinx_book_theme/components/toggle-primary-sidebar.html

@@ -1,3 +1,10 @@
-<button class="sidebar-toggle primary-toggle btn btn-sm" title="Toggle primary sidebar" data-bs-placement="bottom" data-bs-toggle="tooltip">
+{% if sidebars %}
+<button
+  class="sidebar-toggle primary-toggle btn btn-sm"
+  title="Toggle primary sidebar"
+  data-bs-placement="bottom"
+  data-bs-toggle="tooltip"
+>
   <span class="fa-solid fa-bars"></span>
 </button>
+{% endif %}