add image generation tab and fix mobile menu

pages/prompts.html

@@ -10,7 +10,7 @@
 
 <nav>
   <div class="nav-inner">
-    <a href="/" class="nav-brand">AI Cheat Sheet</a>
+    <a href="../index.html" class="nav-brand">AI Cheat Sheet</a>
     <div class="nav-links">
       <a href="/pages/terminology.html">Terminology</a>
       <a href="/pages/techniques.html">Techniques</a>
@@ -19,11 +19,15 @@
       <a href="/pages/prompts.html" class="active">Prompt Guide</a>
       <a href="/pages/math.html">Math & Concepts</a>
       <a href="/pages/chat.html">Chat</a>
+      <a href="/pages/image-gen.html">Image Gen</a>
     </div>
     <button class="dark-toggle" id="darkToggle" aria-label="Toggle dark mode">🌙</button>
   </div>
 </nav>
 
+<button class="menu-toggle" id="menuToggle" aria-label="Toggle menu">☰</button>
+<div class="sidebar-backdrop" id="sidebarBackdrop"></div>
+
 <script>
 (function(){
   var btn = document.getElementById('darkToggle');
@@ -44,6 +48,34 @@
       localStorage.setItem('theme','dark');
     }
   });
+
+  var menuToggle = document.getElementById('menuToggle');
+  var nav = document.querySelector('nav');
+  var backdrop = document.getElementById('sidebarBackdrop');
+  if(menuToggle && nav){
+    menuToggle.addEventListener('click', function(){
+      nav.classList.toggle('sidebar-open');
+      var isOpen = nav.classList.contains('sidebar-open');
+      menuToggle.textContent = isOpen ? '✕' : '☰';
+      if(backdrop){
+        backdrop.classList.toggle('visible', isOpen);
+      }
+    });
+    if(backdrop){
+      backdrop.addEventListener('click', function(){
+        nav.classList.remove('sidebar-open');
+        menuToggle.textContent = '☰';
+        backdrop.classList.remove('visible');
+      });
+    }
+    document.addEventListener('click', function(e){
+      if(nav.classList.contains('sidebar-open') && !nav.contains(e.target) && e.target !== menuToggle){
+        nav.classList.remove('sidebar-open');
+        menuToggle.textContent = '☰';
+        if(backdrop) backdrop.classList.remove('visible');
+      }
+    });
+  }
 })();
 </script>