更改背景显示方式，解决IPAD下输入法引起的背景显示不完全的BUG

src/pages/Login.vue

@@ -1,19 +1,15 @@
 <template>
-  <q-layout
-    view="hHh lpR fFf"
-    :style="
-      landspace
-        ? {
-            'background-image': 'url(login/login_background.png)',
-            'background-size': '100% 100%',
-            'background-repeat': 'no-repeat',
-          }
-        : {}
-    "
-  >
+  <q-layout view="hHh lpR fFf">
+    <img
+      v-if="landspace"
+      src="login/login_background.png"
+      class="fit"
+      style="position: fixed"
+    />
     <q-page-container>
       <q-page
         class="row items-center"
+        style="position: fixed"
         :class="landspace ? '' : 'justify-evenly'"
         :style="landspace ? { left: '50%' } : {}"
       >