diff --git a/cspell.yaml b/cspell.yaml
index c0fbbd094a8..4fdbe6d4b2f 100644
--- a/cspell.yaml
+++ b/cspell.yaml
@@ -327,6 +327,7 @@ words:
   - Vsts
   - vswhere
   - wday
+  - WCAG
   - weidxu
   - westus
   - WHATWG
diff --git a/website/src/components/starlight-overrides/PageFrame.astro b/website/src/components/starlight-overrides/PageFrame.astro
index c2de0a5fe11..2e083b3fe03 100644
--- a/website/src/components/starlight-overrides/PageFrame.astro
+++ b/website/src/components/starlight-overrides/PageFrame.astro
@@ -42,4 +42,27 @@ import Footer from "../footer/footer.astro";
     z-index: 100;
     width: 100%;
   }
+
+  /*
+   * Starlight wraps the docs sidebar in `<nav class="sidebar" aria-label>` but
+   * makes the inner `.sidebar-pane` `position: fixed`. On desktop that leaves
+   * the `<nav>` landmark element itself with an empty, collapsed layout box, so
+   * assistive tech / landmark tools report the visible left navigation as not
+   * belonging to any landmark region (#10793, WCAG 1.3.1). Move the fixed
+   * positioning onto the `<nav>` landmark itself so its bounding box coincides
+   * with the visible sidebar, and let the pane fill it.
+   */
+  @media (min-width: 50rem) {
+    :global(nav.sidebar) {
+      position: fixed;
+      inset-block: var(--sl-nav-height) 0;
+      inset-inline-start: 0;
+      width: var(--sl-sidebar-width);
+    }
+    :global(nav.sidebar > .sidebar-pane) {
+      position: static;
+      width: 100%;
+      height: 100%;
+    }
+  }
 </style>