Multiple Ui fixes (#6272)

* PLT-6453 - Improving headings in the web app

* PLT-6414 - Fixing view members modal issue

* PLT-5863 - Fixing alignment in new channel menu

* PLT-6391 - Fixing code block overlay

webapp/sass/layout/_headers.scss

@@ -26,6 +26,12 @@
         display: inline;
     }
 
+    .member-popover__trigger {
+        & + div {
+            display: none;
+        }
+    }
+
     .member-popover__trigger {
         .fa {
             margin-left: 4px;