Make unloaded statuses follow panel styling

src/components/conversation/conversation.vue

@@ -206,6 +206,7 @@
   </div>
   <div
     v-else
+    class="Conversation -hidden"
     :style="hiddenStyle"
   />
 </template>
@@ -216,6 +217,11 @@
 .Conversation {
   z-index: 1;
 
+  &.-hidden {
+    background: var(--__panel-background);
+    backdrop-filter: var(--__panel-backdrop-filter);
+  }
+
   .conversation-dive-to-top-level-box {
     padding: var(--status-margin);
     border-bottom: 1px solid var(--border);