diff --git a/src/colab-spb-theme-plugin/colab_spb_theme/templates/header_sisp.html b/src/colab-spb-theme-plugin/colab_spb_theme/templates/header_sisp.html
index fdcd613..82a24a9 100644
--- a/src/colab-spb-theme-plugin/colab_spb_theme/templates/header_sisp.html
+++ b/src/colab-spb-theme-plugin/colab_spb_theme/templates/header_sisp.html
@@ -113,6 +113,7 @@
     </div>
   </div>
 </div>
+</header>
 
 {% block main_content %}
   <a name="acontent" id="acontent"></a>
diff --git a/src/colab-spb-theme-plugin/colab_spb_theme/templates/header_spb.html b/src/colab-spb-theme-plugin/colab_spb_theme/templates/header_spb.html
index da0213f..72251b3 100644
--- a/src/colab-spb-theme-plugin/colab_spb_theme/templates/header_spb.html
+++ b/src/colab-spb-theme-plugin/colab_spb_theme/templates/header_spb.html
@@ -151,6 +151,7 @@
     </div>
   </div>
 </div>
+</header>
 
 {% block main_content %}
   <a name="acontent" id="acontent"></a>
--
libgit2 0.21.2