diff --git a/.changeset/grumpy-brooms-study.md b/.changeset/grumpy-brooms-study.md
new file mode 100644
index 00000000000..89110fcf35b
--- /dev/null
+++ b/.changeset/grumpy-brooms-study.md
@@ -0,0 +1,15 @@
+---
+'@astrojs/starlight': minor
+---
+
+Avoids the risk of layout shift when users expand and collapse sidebar groups
+
+This release can introduce additional padding to the site sidebar on certain devices to reserve space for scrollbars. You may wish to inspect your site sidebar visually when upgrading.
+
+If you would prefer to keep the previous styling, you can add the following custom CSS to your site:
+
+```css
+.sidebar-pane {
+  scrollbar-gutter: auto;
+}
+```
diff --git a/packages/starlight/components/PageFrame.astro b/packages/starlight/components/PageFrame.astro
index 5cfb1162049..a72a53086b5 100644
--- a/packages/starlight/components/PageFrame.astro
+++ b/packages/starlight/components/PageFrame.astro
@@ -56,6 +56,7 @@ const { hasSidebar } = Astro.locals.starlightRoute;
 			width: 100%;
 			background-color: var(--sl-color-black);
 			overflow-y: auto;
+			scrollbar-gutter: stable;
 		}
 
 		:global([aria-expanded='true']) ~ .sidebar-pane {