fix inline conversation's shadow showing through outer header

src/components/conversation/conversation.vue

@@ -201,6 +201,8 @@
 @import '../../_variables.scss';
 
 .Conversation {
+  z-index: 1;
+
   .conversation-dive-to-top-level-box {
     padding: var(--status-margin, $status-margin);
     border-bottom-width: 1px;

src/panel.scss

@@ -18,7 +18,7 @@
     bottom: 0;
     left: 0;
     right: 0;
-    z-index: 3;
+    z-index: 5;
     box-shadow: 1px 1px 4px rgba(0, 0, 0, 0.6);
     box-shadow: var(--panelShadow);
     pointer-events: none;
@@ -60,7 +60,7 @@
   padding: 0.6em;
   height: var(--__panel-heading-height);
   line-height: var(--__panel-heading-height-inner);
-  z-index: 3;
+  z-index: 4;
 
   &.-flexible-height {
     --__panel-heading-height: auto;