Disable single toolbar mode and adjust vertical tab button styling

src/browser/app/profile/zen-browser.js

@@ -121,7 +121,7 @@ pref('zen.view.sidebar-height-throttle', 200); // in ms
 pref('zen.view.sidebar-expanded.max-width', 400);
 
 pref('zen.view.show-bottom-border', false);
-pref('zen.view.use-single-toolbar', true);
+pref('zen.view.use-single-toolbar', false, locked);
 
 #ifndef XP_MACOSX
 pref('zen.view.hide-window-controls', true);

src/browser/base/content/zen-styles/zen-tabs/vertical-tabs.css

@@ -644,6 +644,10 @@
   @media (-moz-bool-pref: 'zen.tabs.show-newtab-vertical') {
     #tabs-newtab-button {
       display: flex !important;
+      & .toolbarbutton-text {
+        align-items: center;
+        padding-top: 0;
+      }
     }
 
     #tabbrowser-arrowscrollbox-periphery {