diff --git a/src/zen/compact-mode/ZenCompactMode.mjs b/src/zen/compact-mode/ZenCompactMode.mjs
index 65469e7b7d..a42038d557 100644
--- a/src/zen/compact-mode/ZenCompactMode.mjs
+++ b/src/zen/compact-mode/ZenCompactMode.mjs
@@ -634,6 +634,17 @@ window.gZenCompactModeManager = {
           return;
         }
       }
+      // Don't set hover on toolbar when left sidebar + no bookmarks
+      // (prevents navbar from revealing when it shouldn't)
+      if (
+        isToolbar &&
+        attr === 'zen-has-hover' &&
+        !document.documentElement.hasAttribute('zen-right-side') &&
+        !document.documentElement.hasAttribute('zen-has-bookmarks') &&
+        !element.hasAttribute('should-hide')
+      ) {
+        return;
+      }
       element.setAttribute(attr, 'true');
       if (
         isToolbar &&
diff --git a/src/zen/tabs/zen-tabs.css b/src/zen/tabs/zen-tabs.css
index c285f08016..ba373f452e 100644
--- a/src/zen/tabs/zen-tabs.css
+++ b/src/zen/tabs/zen-tabs.css
@@ -34,10 +34,12 @@
 
     /* Include styles for the top bar under certain conditions:
       * - Bookmarks toolbar is visible OR
-      * - The container is explicitly marked to hide controls (e.g., on Linux with reversed controls)
+      * - The container is explicitly marked to hide controls (e.g., on Linux with reversed controls) OR
+      * - Sidebar is on the left (to prevent flash when toggling bookmarks)
       */
     :root[zen-has-bookmarks] &,
-    &[should-hide='true'] {
+    &[should-hide='true'],
+    :root:not([zen-right-side='true']) & {
 %include zen-tabs/vertical-tabs-topbar.inc.css
     }