Fix sticky header (pydata#1630)

* Fix sticky header

* regression test

Author: gabalafou

src/pydata_sphinx_theme/theme/pydata_sphinx_theme/layout.html

@@ -67,16 +67,14 @@
     <div class="search-button__search-container">{% include "../components/search-field.html" %}</div>
   </div>
 
-  <header>
   {%- if theme_announcement -%}
     {% include "sections/announcement.html" %}
   {%- endif %}
   {% block docs_navbar %}
-    <div class="bd-header navbar navbar-expand-lg bd-navbar">
+    <header class="bd-header navbar navbar-expand-lg bd-navbar">
       {%- include "sections/header.html" %}
-    </div>
+    </header>
   {% endblock docs_navbar %}
-  </header>
 
   <div class="bd-container">
     <div class="bd-container__inner bd-page-width">

tests/test_build.py

@@ -307,6 +307,13 @@ def test_logo_template_rejected(sphinx_build_factory) -> None:
         sphinx_build_factory("base", confoverrides=confoverrides).build()
 
 
+def test_sticky_header(sphinx_build_factory):
+    """Regression test, see #1630. Sticky header should be direct descendant of body."""
+    sphinx_build = sphinx_build_factory("test_navbar_no_in_page_headers").build()
+    index_html = sphinx_build.html_tree("index.html")
+    assert index_html.select_one("body > .bd-header")
+
+
 @pytest.mark.parametrize(
     "align,klass",
     [