diff --git a/doc/sphinx/source/_templates/cross_proj_navbar.html b/doc/sphinx/source/_templates/cross_proj_navbar.html
new file mode 100644
index 0000000000..0c27b67769
--- /dev/null
+++ b/doc/sphinx/source/_templates/cross_proj_navbar.html
@@ -0,0 +1,25 @@
+{% set href = pathto(root_doc) %}
+<nav>
+  <ul class="bd-navbar-elements navbar-nav">
+        <li class="nav-item current active">
+            <a class="nav-link nav-internal" href="{{ href }}">
+            {{ (" ESMValTool ") }}
+            </a>
+        </li>
+        <li class="nav-item ">
+            <a class="nav-link nav-external" href="https://docs.esmvaltool.org/projects/ESMValCore">
+             ESMValCore
+            </a>
+        </li>
+        <li class="nav-item ">
+            <a class="nav-link nav-external" href="https://tutorial.esmvaltool.org/">
+            Tutorial
+            </a>
+        </li>
+        <li class="nav-item ">
+            <a class="nav-link nav-external" href="https://esmvaltool.org/">
+            Website
+            </a>
+        </li>
+  </ul>
+</nav>
diff --git a/doc/sphinx/source/_templates/layout.html b/doc/sphinx/source/_templates/layout.html
index fd48125848..6df4f15011 100644
--- a/doc/sphinx/source/_templates/layout.html
+++ b/doc/sphinx/source/_templates/layout.html
@@ -19,7 +19,9 @@
 
 <style>
 table, th, td {
-  padding: 5px;
+  /* padding: 5px; */
+  padding-left: 30px;
+  padding-right: 30px;
 }
 table {
   border-spacing: 5px;
diff --git a/doc/sphinx/source/_templates/sidebar_nav_lv1.html b/doc/sphinx/source/_templates/sidebar_nav_lv1.html
new file mode 100644
index 0000000000..d5e4c84809
--- /dev/null
+++ b/doc/sphinx/source/_templates/sidebar_nav_lv1.html
@@ -0,0 +1,17 @@
+{# Displays the TOC-subtree for pages nested under the currently active top-level TOCtree element. EDITED #}
+<nav class="bd-docs-nav bd-links"
+     aria-label="{{ _('Section Navigation') }}">
+  <p class="bd-links__title" role="heading" aria-level="1">{{ _("Documentation Navigation") }}</p>
+  <div class="bd-toc-item navbar-nav">
+    {{- generate_toctree_html(
+      startdepth=0,
+      kind="sidebar",
+      show_nav_level=theme_show_nav_level | int,
+      maxdepth=theme_navigation_depth | int,
+      collapse=theme_collapse_navigation | tobool,
+      includehidden=theme_sidebar_includehidden | tobool,
+      titles_only=True
+      )
+    -}}
+  </div>
+</nav>
diff --git a/doc/sphinx/source/conf.py b/doc/sphinx/source/conf.py
index 2802e2a32c..de75f2bde6 100644
--- a/doc/sphinx/source/conf.py
+++ b/doc/sphinx/source/conf.py
@@ -180,6 +180,8 @@
         "image_light": "figures/ESMValTool-logo-2.png",
         "image_dark": "figures/ESMValTool-logo-2-dark.png",
     },
+    "navbar_center": ["cross_proj_navbar"],
+    "search_bar_text": "Search ESMValTool docs... (Also try search in ESMValCore docs)",
 }
 # Add any paths that contain custom themes here, relative to this directory.
 # html_theme_path = []
@@ -224,7 +226,9 @@
 # html_use_smartypants = True
 
 # Custom sidebar templates, maps document names to template names.
-# html_sidebars = {}
+html_sidebars = {
+    "**": ["sidebar_nav_lv1", "sidebar-ethical-ads"]
+}
 
 # Additional templates that should be rendered to pages, maps page names to
 # template names.
@@ -498,7 +502,3 @@
 }
 
 # -- Custom Document processing ----------------------------------------------
-
-import gensidebar
-
-gensidebar.generate_sidebar(globals(), "esmvaltool")
diff --git a/doc/sphinx/source/figures/ESMValSchemaDiagram.png b/doc/sphinx/source/figures/ESMValSchemaDiagram.png
new file mode 100644
index 0000000000..f32a461922
Binary files /dev/null and b/doc/sphinx/source/figures/ESMValSchemaDiagram.png differ
diff --git a/doc/sphinx/source/gensidebar.py b/doc/sphinx/source/gensidebar.py
deleted file mode 100644
index 261d3502a3..0000000000
--- a/doc/sphinx/source/gensidebar.py
+++ /dev/null
@@ -1,85 +0,0 @@
-"""Generates sidebar/toctree.
-
-Generates the common sidebar/toctree for the sphinx/ReadTheDocs
-documentation of the ESMValTool and its subprojects.
-"""
-
-import os
-
-
-def _write_if_changed(fname, contents):
-    """Write/update file only if changed."""
-    try:
-        with open(fname) as stream:
-            old_contents = stream.read()
-    except OSError:
-        old_contents = ""
-
-    if old_contents != contents:
-        with open(fname, "w") as stream:
-            stream.write(contents)
-
-
-def generate_sidebar(conf, conf_api):
-    """Generate sidebar.
-
-    Generate sidebar for ReadTheDocs with links to subprojects and
-    superprojects accordingly.
-    """
-    # determine 'latest' or 'stable'
-    # if not conf.do_gen:
-    do_gen = os.environ.get("SIDEBAR", None) == "1" or conf["on_rtd"]
-
-    lines = ["", ".. DO NOT MODIFY! THIS PAGE IS AUTOGENERATED!", ""]
-
-    def _toctree():
-        lines.extend([".. toctree::", "   :maxdepth: 1", ""])
-
-    def _endl():
-        lines.append("")
-
-    def _write(project, desc, link, mapping=conf["intersphinx_mapping"]):
-        if project != conf_api:
-            if do_gen:
-                args = desc, mapping[project][0], link
-                lines.append("    {} <{}{}.html>".format(*args))
-        else:
-            args = desc, link
-            lines.append("    {} <{}>".format(*args))
-
-    def _header(project, text):
-        if project == conf_api or do_gen:
-            lines.extend([".. toctree::", "   :maxdepth: 2"])
-            lines.extend([f"   :caption: {text}", ""])
-
-    #
-    # Specify the sidebar contents here
-    #
-
-    _header("esmvaltool", "ESMValTool")
-    _write("esmvaltool", "Introduction", "introduction")
-    _write("esmvaltool", "ESMValTool Functionalities", "functionalities")
-    _write("esmvaltool", "Getting started", "quickstart/index")
-    _write("esmvaltool", "Gallery", "gallery")
-    _write("esmvaltool", "Recipes", "recipes/index")
-    _write("esmvaltool", "Obtaining input data", "input")
-    _write("esmvaltool", "Making a recipe or diagnostic", "develop/index")
-    _write("esmvaltool", "Contributing to the community", "community/index")
-    _write("esmvaltool", "Utilities", "utils/utils")
-    _write("esmvaltool", "Diagnostics API Reference", "api/esmvaltool")
-    _write("esmvaltool", "Frequently Asked Questions", "faq")
-    _write("esmvaltool", "Changelog", "changelog")
-    _endl()
-
-    _header("esmvalcore", "ESMValCore")
-    _write("esmvalcore", "Getting started", "quickstart/index")
-    _write("esmvalcore", "Example notebooks", "example-notebooks")
-    _write("esmvalcore", "The recipe format", "recipe/index")
-    _write("esmvalcore", "Diagnostic script interfaces", "interfaces")
-    _write("esmvalcore", "Development", "develop/index")
-    _write("esmvalcore", "Contributing", "contributing")
-    _write("esmvalcore", "ESMValCore API Reference", "api/esmvalcore")
-    _write("esmvalcore", "Changelog", "changelog")
-    _endl()
-
-    _write_if_changed("_sidebar.rst.inc", "\n".join(lines))
diff --git a/doc/sphinx/source/index.rst b/doc/sphinx/source/index.rst
index 136c2eba08..4f768f7fb0 100644
--- a/doc/sphinx/source/index.rst
+++ b/doc/sphinx/source/index.rst
@@ -1,3 +1,5 @@
+:html_theme.sidebar_secondary.remove:
+
 .. ESMValTool documentation master file, created by
    sphinx-quickstart on Tue Jun  2 11:34:13 2015.
    You can adapt this file completely to your liking, but it should at least
@@ -6,12 +8,38 @@
 Welcome to ESMValTool's documentation!
 ======================================
 
+**ESMValTool** is a community diagnostics and performance metrics tool for the evaluation of Earth System Models (ESMs) that allows for
+routine comparison of models and observations. It includes a large collection of community recipes and observation data formatters to CMOR standards.
+
+**ESMValCore** is a software package which provides the core functionality for ESMValTool. It is a workflow to find CMIP data, and apply
+commonly used pre-processing functions.
+
 To get a first impression of what ESMValTool and ESMValCore can do for you,
 have a look at our blog posts
 `Analysis-ready climate data with ESMValCore <https://blog.esciencecenter.nl/easy-ipcc-powered-by-esmvalcore-19a0b6366ea7>`_
 and
 `ESMValTool: Recipes for solid climate science <https://blog.esciencecenter.nl/esmvaltool-recipes-for-solid-climate-science-da5b33814f69>`_.
 
+
+Basic documentation schema
+--------------------------
+This gives a brief idea of topics in each of the packages to help find information. As ESMValTool encompasses ESMValCore there will be some overlap between them.
+The documentation navigation to the left provides more detailed information about ESMValTool.
+`ESMValCore documentation <https://docs.esmvaltool.org/projects/ESMValCore/en/latest/index.html>`_ is also available. ESMValCore can be used without ESMValTool such as in Jupyter
+notebooks.
+
+.. container::
+   :name: figarch
+
+   .. figure:: figures/ESMValSchemaDiagram.png
+      :alt: Brief topics for tool and core.
+      :figclass: align-center
+      :class: dark-light
+
+
+Learning resources:
+-------------------
+
 A tutorial is available on https://tutorial.esmvaltool.org.
 
 A series of video lectures has been created by `ACCESS-NRI <https://access-nri.org.au>`_.
@@ -21,16 +49,36 @@ While these are tailored for ACCESS users, they are still very informative.
 
    <iframe width="560" height="315" src="https://www.youtube.com/embed/videoseries?si=pUXrXB8C8bLRfQHY&amp;list=PLFjfi2xLaFpJp59LvDc1upQsj_xzFlFLc" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>
 
-|
+How to contribute
+-----------------
+Refer to ESMValTool :ref:`contributing to the community<community>` for a guide on contributing recipes and diagnostics.
+
+Refer to ESMValCore contributing for information on contributing code.
 
-For more detailed information, the documentation is available below.
+Get in touch!
+-------------
+Contact information is available :ref:`here <Support-and-Contact>`.
 
-Get in touch! Contact information is available :ref:`here <Support-and-Contact>`.
+.. toctree::
+   :hidden:
+   :maxdepth: 2
+   :caption: ESMValTool
 
-.. include:: _sidebar.rst.inc
+    Introduction <introduction>
+    ESMValTool Functionalities <functionalities>
+    Gallery <gallery>
+    Getting started <quickstart/index>
+    Recipes <recipes/index>
+    Diagnostics API Reference <api/esmvaltool>
+    Obtaining input data <input>
+    Making a recipe or diagnostic <develop/index>
+    Contributing to the community <community/index>
+    Utilities <utils/utils>
+    Frequently Asked Questions <faq>
+    Changelog <changelog>
 
 Indices and tables
-==================
+------------------
 
 * :ref:`genindex`
 * :ref:`search`