diff --git a/sphinx_book_theme/static/sphinx-book-theme.js b/sphinx_book_theme/static/sphinx-book-theme.js
index dfaaa63d..5c558bd6 100644
--- a/sphinx_book_theme/static/sphinx-book-theme.js
+++ b/sphinx_book_theme/static/sphinx-book-theme.js
@@ -30,5 +30,16 @@ var sbRunWhenDOMLoaded = cb => {
     }
 }
 
+// Toggle full-screen with button
+function toggleFullScreen() {
+  if (!document.fullscreenElement) {
+      document.documentElement.requestFullscreen();
+  } else {
+    if (document.exitFullscreen) {
+      document.exitFullscreen();
+    }
+  }
+}
+
 sbRunWhenDOMLoaded(initTriggerNavBar)
 sbRunWhenDOMLoaded(scrollToActive)
diff --git a/sphinx_book_theme/topbar.html b/sphinx_book_theme/topbar.html
index 1f3fe7e9..1617b104 100644
--- a/sphinx_book_theme/topbar.html
+++ b/sphinx_book_theme/topbar.html
@@ -26,6 +26,9 @@
         <!-- Edit this page -->
         {% if theme_use_edit_page_button and github_repo %}<a class="edit-button" href="{{ get_edit_url() }}"><button type="button" class="btn btn-secondary topbarbtn" title="Edit this page"><i class="fas fa-pencil-alt"></i></button></a>{% endif %}
 
+        <!-- Full screen -->
+        <button type="button" class="btn btn-secondary topbarbtn" onclick="toggleFullScreen()" title="Fullscreen mode"><i class="fas fa-expand"></i></button>
+
         <!-- Launch buttons -->
         {% if binder_url or jupyterhub_url or use_thebelab %}
         <div class="dropdown-buttons-trigger">