diff --git a/sphinx_book_theme/layout.html b/sphinx_book_theme/layout.html
index 047f22ba0..35970d7e7 100644
--- a/sphinx_book_theme/layout.html
+++ b/sphinx_book_theme/layout.html
@@ -25,7 +25,7 @@
 <!-- Docs TOC is "d-none d-xl-block col-xl-2" -->
 
 {% block docs_sidebar %}
-<div class="col-12 {{ sidebar_width_class }} bd-sidebar site-navigation show" id="site-navigation">
+<div class="col-12 {{ sidebar_width_class }} bd-sidebar site-navigation show{% if is_single_page %} single-page{% endif %}" id="site-navigation">
     {% if not is_single_page %}
         {% include "sidebar.html" %}
     {%- endif %}
diff --git a/sphinx_book_theme/static/sphinx-book-theme.scss b/sphinx_book_theme/static/sphinx-book-theme.scss
index e8576ca78..0dc75619a 100644
--- a/sphinx_book_theme/static/sphinx-book-theme.scss
+++ b/sphinx_book_theme/static/sphinx-book-theme.scss
@@ -686,6 +686,11 @@ button.topbarbtn img {
             height: 0px !important;
         }
     }
+
+    // If we're only a single page, sidebar should hide at narrow widths.
+    &.single-page {
+        display: none;
+    }
 }
 
 @media (min-width: $breakpoint-md) {