smaller font size

lib/widgets/chat_box.dart

@@ -17,13 +17,6 @@ class ChatBox extends StatelessWidget {
       constraints: const BoxConstraints(
         minHeight: 60,
       ),
-      decoration: BoxDecoration(
-        border: Border.all(
-          color: Colors.grey, // 边框颜色
-          width: 1.0,         // 边框宽度
-        ),
-        borderRadius: BorderRadius.circular(8.0), // 边框圆角
-      ),
       child: ListView.builder(
         controller: scrollController,
         itemCount: messages.length,

lib/widgets/chat_bubble.dart

@@ -82,7 +82,7 @@ class _ChatBubbleState extends State<ChatBubble> {
           _buildStatusRow(hasBottomMargin: true),
           Text(
             message.text,
-            style: TextStyle(color: Colors.white, fontSize: 16),
+            style: TextStyle(color: Colors.white, fontSize: 14),
           )
         ],
       ],
@@ -195,7 +195,7 @@ class _ChatBubbleState extends State<ChatBubble> {
   }
 
   static final MarkdownStyleSheet _markdownStyleSheet = MarkdownStyleSheet(
-    p: const TextStyle(fontSize: 16, color: Colors.white, height: 1.5),
+    p: const TextStyle(fontSize: 14, color: Colors.white, height: 1.5),
     h1: const TextStyle(
         fontSize: 20, fontWeight: FontWeight.bold, color: Colors.white),
     h2: const TextStyle(
@@ -284,7 +284,7 @@ class _ChatBubbleState extends State<ChatBubble> {
                             ? '内容由AI生成，具体以实际情况为准'
                             : 'Generated by AI, for reference only.',
                         style:
-                            const TextStyle(fontSize: 12, color: Colors.grey),
+                            const TextStyle(fontSize: 11, color: Colors.grey),
                       ),
                     ),
                     Row(