diff --git a/docs/sphinx_rtd_theme_chm_friendly/layout.html b/docs/sphinx_rtd_theme_chm_friendly/layout.html
index 56447bbc4..4defabf62 100644
--- a/docs/sphinx_rtd_theme_chm_friendly/layout.html
+++ b/docs/sphinx_rtd_theme_chm_friendly/layout.html
@@ -9,6 +9,10 @@
{%- set lang_attr = 'en' if language == None else (language | replace('_', '-')) %}
{%- set sphinx_writer = 'writer-html5' if html5_doctype else 'writer-html4' %}
+{# Build sphinx_version_info tuple from sphinx_version string in pure Jinja #}
+{%- set (_ver_major, _ver_minor) = (sphinx_version.split('.') | list)[:2] | map('int') -%}
+{%- set sphinx_version_info = (_ver_major, _ver_minor, -1) -%}
+
@@ -22,8 +26,10 @@
{% endblock %}
{# CSS #}
-
-
+ {%- if sphinx_version_info < (4, 0) -%}
+
+
+ {%- endif %}
{%- for css in css_files %}
{%- if css|attr("rel") %}