feat: horizontally center toolbar menu

src/components/UserList.scss

@@ -7,6 +7,10 @@
     display: flex;
     flex-wrap: wrap;
     justify-content: flex-end;
+
+    &:empty {
+      display: none;
+    }
   }
 
   .UserList > * {

src/css/styles.scss

@@ -311,7 +311,7 @@
   }
 
   .App-menu_top {
-    grid-template-columns: 1fr auto 1fr;
+    grid-template-columns: auto max-content auto;
     grid-gap: 4px;
     align-items: flex-start;
     cursor: default;