fix footer issue

src/pages/bookmark.html

@@ -247,9 +247,9 @@
       >
         <div class="max-w-7xl mx-auto px-4 py-3">
           <div class="flex items-center justify-between flex-wrap gap-2">
-            <h1 class="text-xl font-bold text-white" id="filename-display">
+            <div class="text-xl font-bold text-white" id="filename-display">
               PDF Bookmark Editor
-            </h1>
+            </div>
             <div class="flex gap-2 flex-wrap">
               <button
                 id="undo-btn"