Update index.html

index.html

@@ -7,9 +7,10 @@
     <style>
         body {
             background-image: url('https://openai-75050.gzc.vod.tencent-cloud.com/openaiassets_b2edbcb71bed2e127d071803cc655cbf_2579861726125066950.jpg');
-            background-size: cover;
+            background-size: contain; /* 改为 contain 以适应屏幕 */
             background-repeat: no-repeat;
             background-attachment: fixed;
+            background-position: center; /* 居中显示 */
         }
     </style>
 </head>