diff --git a/popup__iframe.html b/popup__iframe.html
index a4eb38e3..37e41902 100644
--- a/popup__iframe.html
+++ b/popup__iframe.html
@@ -162,7 +162,7 @@
         <option value="fn">Fn</option>
         <option value="mouse">Mouse</option>
       </select>
-      <span>layer by holding/pressing this key.</span>
+      <span>layer by <span class="layer-help">holding</span><span class="layer-help" style="display: none;">pressing</span> this key.</span>
     </div>
   </div>
 </script>