diff --git a/packages/web-util/src/components/Header.tsx b/packages/web-util/src/components/Header.tsx
index ac5bc89a6..527fce1b9 100644
--- a/packages/web-util/src/components/Header.tsx
+++ b/packages/web-util/src/components/Header.tsx
@@ -37,6 +37,7 @@ export function Header({
   const closeButton = useRef<HTMLButtonElement>(null);
   useEffect(() => {
     if (!open) return;
+    const toggle = menuButton.current;
     closeButton.current?.focus();
     function closeOnEscape(event: KeyboardEvent): void {
       if (event.key === "Escape") {
@@ -45,7 +46,14 @@ export function Header({
       }
     }
     document.addEventListener("keydown", closeOnEscape);
-    return () => document.removeEventListener("keydown", closeOnEscape);
+    return () => {
+      document.removeEventListener("keydown", closeOnEscape);
+      // Closing removes the focused panel button; return focus to the toggle
+      // instead of leaving it on the page body.
+      if (document.activeElement === document.body) {
+        toggle?.focus();
+      }
+    };
   }, [open]);
   // const ns = useNotifications();
   return (