diff --git a/emccpre.js b/emccpre.js
index b050cf0..f87b576 100644
--- a/emccpre.js
+++ b/emccpre.js
@@ -525,23 +525,20 @@ function initPuzzle() {
             command(4);
     });
 
-    // Event handlers to fake :focus-within on browsers too old for
+    // Event handler to fake :focus-within on browsers too old for
     // it (like KaiOS 2.5).  Browsers without :focus-within are also
-    // too old for focusin/out events, so we have to use focus and
+    // too old for focusin/out events, so we have to use focus events
     // which don't bubble but can be captured.
-    menuform.addEventListener("focus", function(event) {
-        var elem = event.target;
-        while (elem && elem !== menuform) {
+    //
+    // A button losing focus because it was disabled doesn't generate
+    // a blur event, so we do this entirely in the focus handler.
+    document.documentElement.addEventListener("focus", function(event) {
+        for (var elem = event.target; elem; elem = elem.parentElement)
             elem.classList.add("focus-within");
-            elem = elem.parentElement;
-        }
-    }, true);
-    menuform.addEventListener("blur", function(event) {
-        var elem = event.target;
-        while (elem && !elem.contains(event.relatedTarget)) {
-            elem.classList.remove("focus-within");
-            elem = elem.parentElement;
-        }
+        for (elem of
+             Array.from(document.getElementsByClassName("focus-within")))
+            if (!elem.contains(event.target))
+                elem.classList.remove("focus-within");
     }, true);
 
     // Set up the function pointers we haven't already grabbed.