fix: streamline window button positioning and enhance CSS for zen UI layout

src/browser/base/content/ZenUIManager.mjs

@@ -391,12 +391,8 @@ var gZenVerticalTabsManager = {
           } else {
             navBar.append(windowButtons);
           }
-        } else {
+        } else { // not windows styled buttons
-          if (isRightSide) {
+          navBar.appendChild(windowButtons);
-            appContentNavbarContaienr.appendChild(windowButtons);
-          } else {
-            topButtons.prepend(windowButtons);
-          }
         }
       } else if (!isSingleToolbar && isCompactMode) {
         navBar.appendChild(windowButtons);

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

@@ -965,4 +965,26 @@
       padding-left: var(--zen-element-separation);
     }
   }
+
+  :root:not([zen-right-side='true']):not([zen-sidebar-expanded='true'])[zen-window-buttons-reversed='true'] {
+    & #navigator-toolbox {
+      padding-top: var(--zen-toolbar-height);
+    }
+
+    & .titlebar-buttonbox-container {
+      margin-left: calc(-1 * var(--zen-toolbox-max-width)) !important;
+    }
+
+    & #zen-appcontent-wrapper {
+      overflow-x: visible;
+    }
+
+    & #zen-sidebar-top-buttons-customization-target {
+      padding-top: 0;
+    }
+
+    & #zen-appcontent-navbar-container {
+      padding-right: var(--zen-element-separation);
+    }
+  }
 }