diff --git a/docs/index.rst b/docs/index.rst
index eddb21f0..f2310c1c 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -47,6 +47,7 @@ We maintain a list of examples to check our JavaScript client is working correct
 * `Docusaurus <https://test-builds.readthedocs.io/en/docusaurus/>`_
 * `Jekyll <https://test-builds.readthedocs.io/en/jekyll/>`_
 * `Jupyter Book <https://test-builds.readthedocs.io/en/jupyter-book/>`_
+* `mdBook <https://test-builds.readthedocs.io/en/mdbook/>`_
 * `MkDocs <https://test-builds.readthedocs.io/en/mkdocs/>`_
 * `MkDocs (Material theme) <https://test-builds.readthedocs.io/en/mkdocs-material/>`_
 * `MkDocs (Terminal theme) <https://test-builds.readthedocs.io/en/mkdocs-terminal/>`_
diff --git a/src/doctools.css b/src/doctools.css
index 18c31dbb..f4e11cd9 100644
--- a/src/doctools.css
+++ b/src/doctools.css
@@ -6,28 +6,37 @@
  * values.
  **/
 @layer defaults {
+  :root[data-readthedocs-tool="docusaurus"] {
+    --readthedocs-flyout-header-font-size: 0.9rem;
+  }
+
   :root[data-readthedocs-tool="mkdocs-material"] {
     --readthedocs-font-size: 0.58rem;
+    --readthedocs-flyout-header-font-size: 0.7rem;
     --readthedocs-flyout-font-size: 0.58rem;
   }
 
   :root[data-readthedocs-tool="antora"] {
     --readthedocs-font-size: 0.7rem;
+    --readthedocs-flyout-header-font-size: 0.8rem;
     --readthedocs-flyout-font-size: 0.7rem;
   }
 
   :root[data-readthedocs-tool="mdbook"] {
     --readthedocs-font-size: 1.3rem;
+    --readthedocs-flyout-header-font-size: 1.5rem;
     --readthedocs-flyout-font-size: 1.3rem;
   }
 
   :root[data-readthedocs-tool="sphinx"][data-readthedocs-tool-theme="furo"] {
     --readthedocs-font-size: 0.725rem;
+    --readthedocs-flyout-header-font-size: 0.845rem;
     --readthedocs-flyout-font-size: 0.725rem;
   }
 
   :root[data-readthedocs-tool="sphinx"][data-readthedocs-tool-theme="immaterial"] {
     --readthedocs-font-size: 0.58rem;
+    --readthedocs-flyout-header-font-size: 0.7rem;
     --readthedocs-flyout-font-size: 0.58rem;
   }
 }
diff --git a/src/ethicalads.js b/src/ethicalads.js
index 26cd20b8..86e3935d 100644
--- a/src/ethicalads.js
+++ b/src/ethicalads.js
@@ -147,6 +147,28 @@ export class EthicalAdsAddon extends AddonBase {
           placement.classList.add("ethical-alabaster");
           placement.classList.add("ethical-docsify");
 
+          placement.setAttribute("data-ea-type", "readthedocs-sidebar");
+          placement.setAttribute("data-ea-style", "image");
+          knownPlacementFound = true;
+        }
+      } else if (docTool.isAntora()) {
+        selector = "aside nav.nav-menu";
+        element = document.querySelector(selector);
+
+        if (this.elementAboveTheFold(element)) {
+          placement.classList.add("ethical-alabaster");
+
+          placement.setAttribute("data-ea-type", "readthedocs-sidebar");
+          placement.setAttribute("data-ea-style", "image");
+          knownPlacementFound = true;
+        }
+      } else if (docTool.isMdBook()) {
+        selector = "nav#sidebar mdbook-sidebar-scrollbox";
+        element = document.querySelector(selector);
+
+        if (this.elementAboveTheFold(element)) {
+          placement.classList.add("ethical-alabaster");
+
           placement.setAttribute("data-ea-type", "readthedocs-sidebar");
           placement.setAttribute("data-ea-style", "image");
           knownPlacementFound = true;