优化 整体UI调整

src/App.tsx

@@ -53,18 +53,24 @@ function AppContent() {
   }, [setShowPromptPanel, setShowHistory]);
 
   return (
-    <div className="h-screen bg-white text-gray-900 flex flex-col font-sans">
-      <Header />
+    <div className="h-screen bg-gray-50 text-gray-900 flex flex-col font-sans">
+      <div className="shadow-sm">
+        <Header />
+      </div>
       
       <div className="flex-1 flex overflow-hidden">
         <div className={cn("flex-shrink-0 transition-all duration-300", !showPromptPanel && "w-8")}>
-          <PromptComposer />
+          <div className="h-full shadow-lg">
+            <PromptComposer />
+          </div>
         </div>
         <div className="flex-1 min-w-0">
           <ImageCanvas />
         </div>
         <div className="flex-shrink-0">
-          <HistoryPanel />
+          <div className="h-full shadow-lg">
+            <HistoryPanel />
+          </div>
         </div>
       </div>
     </div>