diff --git a/src/browser/base/content/ZenCustomizableUI.sys.mjs b/src/browser/base/content/ZenCustomizableUI.sys.mjs
index b4a22ae10..c2359b748 100644
--- a/src/browser/base/content/ZenCustomizableUI.sys.mjs
+++ b/src/browser/base/content/ZenCustomizableUI.sys.mjs
@@ -45,6 +45,7 @@ export var ZenCustomizableUI = new (class {
         customizationtarget="zen-sidebar-top-buttons-customization-target"
         mode="icons">
         <hbox id="zen-sidebar-top-buttons-customization-target" class="customization-target" flex="1">
+          <toolbarbutton hidden="true" removable="true" class="chromeclass-toolbar-additional toolbarbutton-1 zen-sidebar-action-button" id="zen-expand-sidebar-button" data-l10n-id="sidebar-zen-expand" cui-areatype="toolbar" oncommand="gZenVerticalTabsManager.toggleExpand();"></toolbarbutton>
           <toolbarbutton removable="true" class="toolbarbutton-1 zen-sidebar-action-button zen-compact-mode-ignore" id="zen-sidepanel-button" data-l10n-id="sidebar-zen-sidepanel" onclick="gZenBrowserManagerSidebar.toggle();"></toolbarbutton>
         </hbox>
       </toolbar>
diff --git a/src/browser/base/content/ZenUIManager.mjs b/src/browser/base/content/ZenUIManager.mjs
index 7164f371e..8d6427e27 100644
--- a/src/browser/base/content/ZenUIManager.mjs
+++ b/src/browser/base/content/ZenUIManager.mjs
@@ -305,7 +305,7 @@ var gZenVerticalTabsManager = {
         }
       } else {
         if (isRightSide) {
-          document.getElementById('zen-appcontent-navbar-container').prepend(windowButtons);
+          document.getElementById('zen-appcontent-navbar-container').appendChild(windowButtons);
         } else {
           topButtons.prepend(windowButtons);
         }
diff --git a/src/browser/base/content/zen-styles/zen-compact-mode.css b/src/browser/base/content/zen-styles/zen-compact-mode.css
index f3fd01c04..8f6f79374 100644
--- a/src/browser/base/content/zen-styles/zen-compact-mode.css
+++ b/src/browser/base/content/zen-styles/zen-compact-mode.css
@@ -24,7 +24,7 @@
         --zen-compact-float: calc(var(--zen-element-separation) - 1px);
         position: absolute;
         z-index: 10;
-        transition: transform 0.2s ease-in-out, opacity 0.2s ease-in-out;
+        transition: top 0.2s ease-in-out, opacity 0.2s ease-in-out;
         right: calc(100% - var(--zen-element-separation));
         top: 0;
         bottom: var(--zen-element-separation);
diff --git a/src/browser/base/content/zen-styles/zen-decks.css b/src/browser/base/content/zen-styles/zen-decks.css
index 1bb51b0b1..d02a7b523 100644
--- a/src/browser/base/content/zen-styles/zen-decks.css
+++ b/src/browser/base/content/zen-styles/zen-decks.css
@@ -27,7 +27,8 @@
 
 #tabbrowser-tabpanels[zen-split-view='true'] > [zen-split='true'], #zen-splitview-dropzone {
   flex: 1;
-  margin: calc(var(--zen-split-column-gap) / 2) calc(var(--zen-split-row-gap) / 2 + 1px);
+  margin: calc(var(--zen-split-column-gap) / 2) calc(var(--zen-split-row-gap) / 2 + 1px) !important;
+  margin-bottom: 0 !important;
   position: absolute !important;
   overflow: hidden;
 }
@@ -48,9 +49,15 @@
   outline-offset: -1px;
 }
 
-#tabbrowser-tabbox {
+#tabbrowser-tabbox:has(#tabbrowser-tabpanels[zen-split-view='true']) {
   --zen-split-row-gap: calc(var(--zen-element-separation) + 1px);
   --zen-split-column-gap: calc(var(--zen-element-separation) + 1px);
+  margin-right: calc(-1 * var(--zen-split-column-gap));
+
+  :root[zen-right-side='true'] & {
+    margin-right: 0;
+    margin-left: calc(-1 * var(--zen-split-column-gap));
+  }
 }
 
 #tabbrowser-tabpanels:has(> [zen-split='true']), #zen-splitview-overlay {