perf:聊天室背景全屏

src/components/websocket/Onlinewebsocket.vue

@@ -637,8 +637,11 @@ export default {
   margin: 0;
   padding: 0;
   background: url(https://w.wallhaven.cc/full/72/wallhaven-72wzq9.png);
-  /* background-size: cover; */
-  background-repeat: repeat-y;
+  background-position: center center;
+  background-clip: border-box;
+  background-size:100% 100%;
+  background-attachment:fixed;
+  background-repeat: no-repeat;
 }
 
 /* 取消滚动并且隐藏 */