docutils 0.17+'s HTML5 writer writes <section> instead of <div class="section">.

Author: ffplexim

src/theme.js

@@ -136,7 +136,7 @@ function ThemeNav () {
                 // Find associated id element, then its closest section
                 // in the document and try with that one.
                 var id_elt = $('.document [id="' + anchor.substring(1) + '"]');
-                var closest_section = id_elt.closest('div.section');
+                var closest_section = id_elt.closest("section");
                 link = vmenu.find('[href="#' + closest_section.attr("id") + '"]');
                 if (link.length === 0) {
                     // still not found in the sidebar. fall back to main section