改了ai聊天的格式

pages/ai/aichat.wxss

@@ -97,16 +97,16 @@
 /* 消息项 */
 .message-item {
   display: flex;
+  flex-direction: column;
   padding: 16rpx 24rpx;
-  align-items: flex-start;
 }
 
 .message-item.ai {
-  justify-content: flex-start;
+  align-items: flex-start;
 }
 
 .message-item.user {
-  justify-content: flex-end;
+  align-items: flex-end;
 }
 
 /* 头像 */
@@ -122,7 +122,7 @@
 
 .ai-avatar {
   background: linear-gradient(135deg, #FF9B33 0%, #FF7A33 100%);
-  margin-right: 16rpx;
+  margin-bottom: 12rpx;
   padding: 16rpx;
   width: 46rpx;
   height: 46rpx;
@@ -130,14 +130,14 @@
 
 .user-avatar {
   background: linear-gradient(135deg, #4CAF50 0%, #45A049 100%);
-  margin-left: 16rpx;
+  margin-bottom: 12rpx;
 }
 
 /* 消息内容 */
 .message-content {
   display: flex;
   flex-direction: column;
-  max-width: 70%;
+  max-width: 95%;
 }
 
 .message-item.user .message-content {