toolbar below content: remove totally unnecessary css nesting

chrome/toolbars_below_content_v2.css

@@ -9,8 +9,7 @@ See the above repository for updates as well as full license text. */
 #navigator-toolbox{
   display: contents;
 }
-#main-window > body{
-  > #browser,
+#main-window > body > #browser,
 .global-notificationbox,
  #tab-notification-deck,
  #toolbar-menubar{
@@ -30,7 +29,7 @@ See the above repository for updates as well as full license text. */
   height: calc(var(--urlbar-min-height) - 2px - 2 * var(--urlbar-container-padding));
 }
 .urlbarView-body-inner{ border-top-style: none !important; }
-}
+
 @media (-moz-bool-pref: "userchrome.toolbars-below-content.tabs-at-bottom.enabled"){
   #TabsToolbar{
     order: 3