diff --git a/src/browser/base/content/ZenUIManager.mjs b/src/browser/base/content/ZenUIManager.mjs
index 35556dfd9..347309f6f 100644
--- a/src/browser/base/content/ZenUIManager.mjs
+++ b/src/browser/base/content/ZenUIManager.mjs
@@ -28,17 +28,26 @@ var gZenUIManager = {
 
 var gZenVerticalTabsManager = {
   init() {
-    Services.prefs.addObserver('zen.view.sidebar-expanded', this._updateEvent.bind(this));
-    Services.prefs.addObserver('zen.view.sidebar-expanded.max-width', this._updateEvent.bind(this));
-    Services.prefs.addObserver('zen.view.sidebar-expanded.on-hover', this._updateOnHoverVerticalTabs.bind(this));
-    this._updateMaxWidth();
+    var updateEvent = this._updateEvent.bind(this);
+    Services.prefs.addObserver('zen.view.sidebar-expanded', updateEvent);
+    Services.prefs.addObserver('zen.tabs.vertical.right-side', updateEvent);
+    Services.prefs.addObserver('zen.view.sidebar-expanded.max-width', updateEvent);
+    Services.prefs.addObserver('zen.view.sidebar-expanded.on-hover', updateEvent);
+    this._updateEvent();
     this.initRightSideOrderContextMenu();
-    this._updateOnHoverVerticalTabs();
+  },
+
+  get navigatorToolbox() {
+    if (this._navigatorToolbox) {
+      return this._navigatorToolbox;
+    }
+    this._navigatorToolbox = document.getElementById('navigator-toolbox');
+    return this._navigatorToolbox;
   },
 
   _updateOnHoverVerticalTabs() {
     let onHover = Services.prefs.getBoolPref('zen.view.sidebar-expanded.on-hover');
-    let sidebar = document.getElementById('navigator-toolbox');
+    let sidebar = this.navigatorToolbox;
     if (onHover) {
       sidebar.setAttribute('zen-user-hover', 'true');
     } else {
@@ -62,7 +71,19 @@ var gZenVerticalTabsManager = {
   },
 
   _updateEvent() {
+    console.log('ZenThemeModifier: update event');
     this._updateMaxWidth();
+    if (Services.prefs.getBoolPref('zen.view.sidebar-expanded')) {
+      this.navigatorToolbox.setAttribute('zen-expanded', 'true');
+    } else {
+      this.navigatorToolbox.removeAttribute('zen-expanded');
+    }
+    if (Services.prefs.getBoolPref('zen.tabs.vertical.right-side')) {
+      this.navigatorToolbox.setAttribute('zen-right-side', 'true');
+    } else {
+      this.navigatorToolbox.removeAttribute('zen-right-side');
+    }
+    this._updateOnHoverVerticalTabs();
   },
 
   _updateMaxWidth() {
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 19dc05ef6..f1e433268 100644
--- a/src/browser/base/content/zen-styles/zen-compact-mode.css
+++ b/src/browser/base/content/zen-styles/zen-compact-mode.css
@@ -30,7 +30,7 @@
       border: 1px solid var(--zen-colors-border);
       transition-delay: 200ms;
       background: var(--zen-colors-tertiary) !important;
-      padding: 0 5px;
+      padding: var(--zen-toolbox-padding);
       border-radius: var(--zen-panel-radius);
     }
 
@@ -40,13 +40,14 @@
 
     &,
     & #titlebar {
-      min-width: calc(var(--zen-navigation-toolbar-min-width) + var(--zen-compact-toolbox-margin-single) * 4) !important;
+      min-width: var(--zen-toolbox-min-width) !important;
     }
   }
 
   @media not (-moz-bool-pref: 'zen.view.sidebar-expanded') {
     #navigator-toolbox {
       width: fit-content !important;
+      --zen-toolbox-max-width: calc(50px + var(--zen-compact-toolbox-margin-single) * 2) !important;
     }
   }
 
@@ -186,33 +187,29 @@
       padding-top: var(--zen-element-separation) !important;
     }
 
-    #titlebar {
-      padding-top: 5px !important;
-    }
-
     #zen-sidebar-web-panel-wrapper {
       margin-top: 10px !important;
     }
   }
 
-  @media (-moz-bool-pref: 'zen.tabs.vertical.right-side') {
-    #navigator-toolbox {
+  #navigator-toolbox[zen-right-side='true'] {
+    & {
       right: 0 !important;
       transform: translateX(calc(100% - (var(--zen-compact-toolbox-margin-single) / 2))) !important;
     }
 
-    #navigator-toolbox > vbox {
+    & > vbox {
       float: right;
     }
 
-    #navigator-toolbox:hover,
-    #navigator-toolbox:focus-within,
-    #navigator-toolbox[zen-user-show],
-    #navigator-toolbox[flash-popup],
-    #navigator-toolbox[movingtab],
-    #mainPopupSet:has(> #appMenu-popup:hover) ~ toolbox,
-    #navigator-toolbox:has(.tabbrowser-tab:active),
-    #navigator-toolbox:has(*[open='true']:not(tab):not(#zen-sidepanel-button)) {
+    &:hover,
+    &:focus-within,
+    &[zen-user-show],
+    &[flash-popup],
+    &[movingtab],
+    & #mainPopupSet:has(> #appMenu-popup:hover) ~ toolbox,
+    &:has(.tabbrowser-tab:active),
+    &:has(*[open='true']:not(tab):not(#zen-sidepanel-button)) {
       transform: none !important;
       opacity: 1;
 
diff --git a/src/browser/base/content/zen-styles/zen-sidebar.css b/src/browser/base/content/zen-styles/zen-sidebar.css
index b0e2cb48a..bef93af65 100644
--- a/src/browser/base/content/zen-styles/zen-sidebar.css
+++ b/src/browser/base/content/zen-styles/zen-sidebar.css
@@ -1,117 +1,6 @@
-/*
- * This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/.
- */
 
-:root {
-  --sidebar-background-color: var(--toolbar-bgcolor) !important;
-  --zen-sidebar-box-shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
-}
-
-#sidebar-box {
-  --zen-sidebar-box-border-radius: var(--zen-panel-radius);
-  margin: var(--zen-element-separation);
-  border-radius: var(--zen-sidebar-box-border-radius);
-  overflow: hidden;
-  transition: 0.2s;
-  margin-left: 0;
-  border: var(--zen-appcontent-border);
-  box-shadow: none;
-  margin-top: 0;
-}
-
-#sidebar-box[hidden='true'] {
-  width: 0;
-  opacity: 0;
-}
-
-#sidebar-box:not([positionend='true']) {
-  margin-right: 0;
-}
-
-#zen-main-app-wrapper:has(#sidebar-box:not([hidden='true'], [positionend='true'])) #TabsToolbar {
-  margin-right: 0 !important;
-  box-shadow: none !important;
-}
-
-#sidebar-splitter {
-  /* we can still use the splitter but we can't see it */
-  background: transparent !important;
-  border-color: transparent !important;
-  width: 1px !important;
-  margin-right: 5px;
-}
-
-#sidebar-box[positionend] {
-  margin-left: 0;
-}
-
-.zen-sidebar-action-button {
-  --toolbarbutton-active-background: var(--zen-colors-secondary);
-  width: var(--zen-sidebar-action-button-width);
-  height: var(--zen-sidebar-action-button-width);
-  padding: 0;
-  margin: 0;
-  display: flex;
-  justify-content: center;
-  align-items: center;
-}
-
-#TabsToolbar .toolbarbutton-1 {
-  width: var(--zen-sidebar-action-button-width);
-  height: var(--zen-sidebar-action-button-width);
-  margin-left: auto !important;
-  margin-right: auto !important;
-}
-
-#TabsToolbar .toolbarbutton-1:not(.zen-sidebar-panel-button) > :is(.toolbarbutton-icon, .toolbarbutton-badge-stack),
-.zen-sidebar-action-button {
-  border-radius: 8px !important;
-}
-
-:root[customizing] #navigator-toolbox {
-  display: none;
-}
-
-.zen-sidebar-action-button:hover {
-  background: var(--toolbarbutton-hover-background) !important;
-}
-
-.zen-sidebar-action-button:hover image {
-  background: transparent !important;
-}
-
-#sidebar-box[hidden='true'] .zen-sidebar-action-button,
-.zen-sidebar-panel-button[animate] {
-  opacity: 0;
-  transform: translateX(-110%);
-  animation: zen-sidebar-button-fadeIn 0.4s forwards;
-}
-
-@keyframes zen-sidebar-button-fadeIn {
-  0% {
-    transform: translateX(-110%);
-    opacity: 0;
-  }
-  100% {
-    opacity: 1;
-    transform: translateX(0);
-  }
-}
-
-/* Icons */
-
-#zen-preferences-button {
-  list-style-image: url('chrome://global/skin/icons/settings.svg');
-}
-
-#zen-history-button {
-  list-style-image: url('chrome://browser/skin/history.svg');
-}
-
-#zen-bookmark-button {
-  list-style-image: url(chrome://browser/skin/bookmark-hollow.svg);
+toolbar {
+  min-height: 46px;
 }
 
 #zen-profile-button {
@@ -119,136 +8,26 @@
   justify-content: center;
   position: relative;
   align-items: center;
-}
-
-#zen-profile-button::before {
-  background-image: var(--avatar-image-url);
-  border-radius: 50%;
-  background-size: cover;
-  background-position: center;
-  width: 20px;
-  height: 20px;
-  border: 2px solid var(--zen-colors-border);
-  content: '';
-  top: 50%;
-  left: var(--toolbar-start-end-padding);
-  transform: translateY(-50%);
-  position: absolute;
-}
-
-/* Ugly code */
-
-#TabsToolbar .zen-sidebar-action-button:nth-child(1),
-.zen-sidebar-panel-button:nth-child(1) {
-  animation-delay: 0.1s;
-}
-#TabsToolbar .zen-sidebar-action-button:nth-child(2),
-.zen-sidebar-panel-button:nth-child(2) {
-  animation-delay: 0.2s;
-}
-#TabsToolbar .zen-sidebar-action-button:nth-child(3),
-.zen-sidebar-panel-button:nth-child(3) {
-  animation-delay: 0.3s;
-}
-#TabsToolbar .zen-sidebar-action-button:nth-child(4),
-.zen-sidebar-panel-button:nth-child(4) {
-  animation-delay: 0.4s;
-}
-#TabsToolbar .zen-sidebar-action-button:nth-child(5),
-.zen-sidebar-panel-button:nth-child(5) {
-  animation-delay: 0.5s;
-}
-#TabsToolbar .zen-sidebar-action-button:nth-child(6),
-.zen-sidebar-panel-button:nth-child(6) {
-  animation-delay: 0.6s;
-}
-#TabsToolbar .zen-sidebar-action-button:nth-child(7),
-.zen-sidebar-panel-button:nth-child(7) {
-  animation-delay: 0.7s;
-}
-#TabsToolbar .zen-sidebar-action-button:nth-child(8),
-.zen-sidebar-panel-button:nth-child(8) {
-  animation-delay: 0.8s;
-}
-#TabsToolbar .zen-sidebar-action-button:nth-child(9),
-.zen-sidebar-panel-button:nth-child(9) {
-  animation-delay: 0.9s;
-}
-#TabsToolbar .zen-sidebar-action-button:nth-child(10),
-.zen-sidebar-panel-button:nth-child(10) {
-  animation-delay: 1s;
-}
-
-#zen-sidebar-icons-wrapper toolbarbutton {
+  list-style-image: var(--avatar-image-url);
   position: relative;
-}
 
-#zen-sidebar-icons-wrapper {
-  display: flex;
-  flex-direction: column;
-  margin: 0 var(--zen-tabbrowser-padding);
-  position: relative;
-  background: transparent !important;
-  align-items: center;
-  justify-content: end;
-  min-height: fit-content;
-  --zen-sidebar-action-content-separator: calc(5px + var(--zen-tabbrowser-padding));
-  padding-top: var(--zen-sidebar-action-content-separator);
-  color-scheme: inherit !important;
-}
-
-#alltabs-button {
-  &:hover .toolbarbutton-badge-stack {
-    background: transparent !important;
-  }
-}
-
-#zen-sidebar-icons-wrapper::before {
-  content: '';
-  position: absolute;
-  top: 0;
-  left: 50%;
-  transform: translateX(-50%);
-  width: 60%;
-  height: 1px;
-  background: var(--zen-colors-border);
-}
-
-#zen-sidepanel-button[hidden='true'] {
-  display: none;
-}
-
-#zen-expand-sidebar-button {
-  display: none;
-}
-
-:root:not([inDOMFullscreen='true']) #zen-sidebar-splitter {
-  display: block;
-  width: var(--zen-tabbrowser-padding);
-  opacity: 0;
-}
-
-:root[inDOMFullscreen='true'] #zen-sidebar-splitter {
-  display: none;
-}
-
-@media not (-moz-bool-pref: 'zen.view.sidebar-expanded') {
-  #navigator-toolbox {
-    width: 0;
-    padding-right: 2px;
-  }
-
-  #zen-sidebar-splitter {
-    display: none !important;
-  }
-}
-
-@media (-moz-bool-pref: 'zen.view.sidebar-expanded.show-button') {
-  #zen-expand-sidebar-button {
+  & image {
     display: flex;
+    justify-content: center;
+    align-items: center;
+    padding: 8px;
   }
 }
 
-:root:is([chromehidden~='location'], [chromehidden~='toolbar']) #navigator-toolbox {
-  display: none !important;
-}
+/*#zen-profile-button::before {
+  background: transparent;
+  border-radius: 50%;
+  border: 3px solid var(--zen-colors-border);
+  position: absolute;
+  content: "";
+  top: 50%;
+  left: 50%;
+  transform: translate(-50%, -50%);
+  width: calc(2 * var(--toolbarbutton-inner-padding) + 16px - 8px - var(--toolbarbutton-inner-padding));
+  height: calc(2 * var(--toolbarbutton-inner-padding) + 16px - 8px - var(--toolbarbutton-inner-padding));
+}*/
diff --git a/src/browser/base/content/zen-styles/zen-tabs.css b/src/browser/base/content/zen-styles/zen-tabs.css
index 12bd7991f..6ac218e66 100644
--- a/src/browser/base/content/zen-styles/zen-tabs.css
+++ b/src/browser/base/content/zen-styles/zen-tabs.css
@@ -5,3 +5,9 @@
 #zen-tabbox-wrapper {
   position: relative;
 }
+
+@media (-moz-bool-pref: 'zen.workspaces.hide-default-container-indicator') {
+  .tabbrowser-tab[zenDefaultUserContextId='true'] .tab-context-line {
+    display: none !important;
+  }
+}
diff --git a/src/browser/base/content/zen-styles/zen-tabs/vertical-tabs.css b/src/browser/base/content/zen-styles/zen-tabs/vertical-tabs.css
index 645cd6b37..da846d8c2 100644
--- a/src/browser/base/content/zen-styles/zen-tabs/vertical-tabs.css
+++ b/src/browser/base/content/zen-styles/zen-tabs/vertical-tabs.css
@@ -1,481 +1,194 @@
 @media (-moz-bool-pref: 'zen.tabs.vertical') {
-  #titlebar {
+
+  #tabbrowser-tabs,
+  #TabsToolbar,
+  #titlebar,
+  #TabsToolbar-customization-target {
+    flex-direction: column;
     height: 100%;
   }
 
-  #vertical-pinned-tabs-container {
-    padding-inline-end: 0 !important;
-    max-height: unset !important;
-    overflow: visible !important;
-    gap: 4px;
+  #browser {
+    --zen-toolbox-padding: 5px;
+    --zen-toolbox-top-align: var(--zen-toolbox-padding);
+  }
 
-    & .tabbrowser-tab:not(:hover):not([selected]):not([multiselected]) {
-      background: color-mix(in srgb, var(--zen-colors-secondary) 20%, transparent 80%);
+  #navigator-toolbox {
+    --border-radius-medium: 8px;
+    --tab-border-radius: var(--border-radius-medium);
+    --zen-toolbox-min-width: 1px;
+
+    min-width: var(--zen-toolbox-min-width);
+
+    padding: var(--zen-toolbox-padding);
+    padding-top: var(--zen-toolbox-top-align);
+  }
+
+
+  #TabsToolbar-customization-target {
+    gap: var(--zen-toolbox-padding);
+  }
+
+  #tabbrowser-tabs {
+    margin-inline-start: 0 !important;
+    padding-inline-start: 0 !important;
+    grid-gap: 2px !important;
+
+    border-bottom: 1px solid var(--zen-colors-border) !important;
+
+    --tab-block-margin: 2px;
+
+    & .tabbrowser-tab {
+      max-width: unset !important;
+      padding: 0 !important;
+
+      & .tab-background {
+        overflow: hidden;
+
+        & .tab-context-line {
+          margin: 0 0px !important;
+          width: 3px !important;
+        }
+      }
     }
   }
 
-  #tabs-newtab-button {
-    display: none !important;
+  #zen-sidebar-icons-wrapper {
+    background: transparent;
   }
 
   #newtab-button-container {
     margin-inline-end: 0 !important;
-    margin-top: 0;
-    margin-bottom: calc(var(--space-small) / 2);
-    position: relative;
     padding-top: 0 !important;
-
-    --zen-sidebar-action-button-width: 35px;
-    :root[uidensity='compact'] & {
-      --zen-sidebar-action-button-width: 30px;
-    }
+    border-top: solid transparent 0px !important;
 
     &[showborder] {
-      margin-top: var(--space-small);
-      border-top: 0px solid transparent !important;
-      padding-top: var(--space-small) !important;
+      padding-top: 4px !important;
     }
   }
 
-  #navigator-toolbox {
-    margin-top: 0; /* Issue #156 */
-    order: 0 !important;
-  }
+  #vertical-pinned-tabs-container {
+    padding-inline-end: 0 !important;
+    gap: 3px !important;
+    max-height: unset !important;
+    overflow: visible !important;
 
-  #zen-sidebar-splitter {
-    order: 0 !important;
-  }
+    & .tab-background:not(:hover):not([selected]):not([multiselected]) {
+      background: color-mix(in srgb, var(--zen-colors-secondary) 20%, transparent 80%) !important;
+    }
 
-  #navigator-toolbox {
-    margin-top: 0 !important;
-  }
-
-  #zen-tabbox-wrapper:has(#zen-sidebar-splitter:not([state='dragging'])) #navigator-toolbox {
-    transition: 0.3s;
-  }
-
-  #navigator-toolbox toolbar#TabsToolbar {
-    margin: var(--zen-appcontent-separator-from-window);
-    overflow: hidden;
-    transition: 0.2s;
-    flex-direction: column;
-    padding: 5px 0;
-    margin-right: 0;
-    -moz-window-dragging: no-drag;
-    --zen-sidebar-action-button-width: 38px;
-    padding-bottom: calc(5px + 5px); /* Taking into consideration the padding of the sidebar without being inlined */
-
-    :root[zen-sidebar-legacy='true'] & {
-      padding-top: 0 !important;
+    & .tabbrowser-tab .tab-content {
+      display: flex;
+      align-items: center;
+      justify-content: center;
     }
   }
 
-  #TabsToolbar-customization-target {
-    flex-direction: column;
-    max-width: 100%;
-  }
+  /* Mark: toolbox as expanded */
+  #navigator-toolbox:is(
+    #navigator-toolbox[zen-user-hover='true']:hover,
+    #navigator-toolbox[zen-user-hover='true']:focus-within,
+    #mainPopupSet[zen-user-hover='true']:has(> #appMenu-popup:hover) ~ toolbox,
+    #navigator-toolbox[zen-user-hover='true']:has(*[open='true']:not(tab):not(#zen-sidepanel-button)),
+    #navigator-toolbox[zen-expanded='true']:not([zen-user-hover='true'])) {
+    --zen-toolbox-min-width: 150px;
 
-  :root[customizing] .customization-target:not(#widget-overflow-fixed-list) {
-    min-width: 0;
-  }
+    & #zen-sidebar-icons-wrapper {
+      display: grid;
+      /* Make sure the icons take most of the space, smartly */
+      grid-template-columns: repeat(auto-fit, minmax(var(--collapsed-tab-width), auto));
+      gap: 4px;
 
-  toolbarpaletteitem {
-    justify-content: center;
-  }
-
-  toolbarbutton#scrollbutton-down,
-  toolbarbutton#scrollbutton-up {
-    display: none;
-  }
-
-  #toolbar-menubar {
-    display: none;
-  }
-
-  .tab-label-container {
-    display: none;
-  }
-
-  .tab-icon-stack > .tab-icon-image,
-  .tab-icon-stack > .tab-throbber {
-    width: var(--zen-browser-tab-icon-size);
-    height: var(--zen-browser-tab-icon-size);
-    margin-inline-end: 0;
-  }
-
-  .tab-icon-stack .tab-icon-image {
-    transform: scale(0.5);
-    opacity: 0;
-    animation: zen-zoom-in 0.12s ease-in-out 0.3s forwards;
-  }
-
-  .tab-background {
-    display: none;
-  }
-
-  .tabbrowser-tab {
-    --zen-browser-tab-icon-size: 16px;
-    --tab-min-width: 36px;
-    margin: 0 auto;
-    border-radius: 8px;
-    position: relative;
-    color-scheme: var(--tab-selected-color-scheme);
-    border: 2px solid transparent;
-    background: transparent;
-    padding: 0;
-    align-items: center;
-    min-height: var(--tab-min-width); /* Make a box */
-    animation: zen-slide-in 0.3s;
-    width: calc(var(--zen-browser-tab-icon-size) + 2px);
-    transition:
-      0.1s background,
-      0.1s border-color;
-    min-width: var(--tab-min-width);
-    display: flex;
-    justify-content: center;
-    align-items: center;
-  }
-
-  @media (-moz-bool-pref: 'zen.tabs.dim-pending') {
-    .tabbrowser-tab[pending]:not(:hover) {
-      opacity: 0.5;
+      padding-top: calc(var(--zen-toolbox-padding) * 2);
     }
-  }
 
-  .tabbrowser-tab[hidden='true'] {
-    display: none;
-  }
-
-  .tabbrowser-tab:hover {
-    background: var(--toolbarbutton-hover-background);
-  }
-
-  .tabbrowser-tab:active,
-  .zen-sidebar-panel-button:active {
-    transform: scale(0.9);
-  }
-
-  .tab-stack {
-    width: 30px;
-    height: 30px;
-    min-width: 30px;
-    min-height: 30px;
-    position: relative;
-    display: flex;
-    align-items: center;
-    justify-content: center;
-  }
-
-  .tabbrowser-tab:not([fadein]) {
-    display: none;
-  }
-
-  .tabbrowser-tab:is([multiselected='true'], [selected]) {
-    background: var(--toolbarbutton-hover-background);
-  }
-
-  #private-browsing-indicator-with-label {
-    display: none;
-  }
-
-  .tabbrowser-tab::before {
-    /* Containers */
-    background: var(--identity-tab-color, transparent);
-    border-radius: 2px;
-    height: 80%;
-    width: 2px;
-    position: absolute;
-    top: 50%;
-    transform: translateY(-50%);
-    left: -2px;
-    content: '';
-    pointer-events: none;
-  }
-
-  @media (-moz-bool-pref: 'zen.workspaces.hide-default-container-indicator') {
-    .tabbrowser-tab[zenDefaultUserContextId='true']::before {
-      display: none;
+    /* Mark: Fix separator paddings */
+    &[zen-right-side='true'] {
+      padding-left: 0 !important;
     }
-  }
 
-  .tabbrowser-tab {
-    margin-inline-start: 0;
-    margin: 0 auto;
-    margin-bottom: 1.5px;
-  }
-
-  .tabbrowser-tab[pinned] {
-    position: relative;
-    display: flex;
-  }
-
-  .tab-close-button {
-    position: absolute;
-    display: none;
-    left: 0;
-    top: 50%;
-  }
-
-  .tabbrowser-tab[open='true']:hover .tab-close-button {
-    /* TODO: fix this */
-    /*display: block;*/
-  }
-
-  .tab-content {
-    padding: 0;
-    width: fit-content;
-
-    &[pinned] {
-      padding: 0 !important;
+    &:not([zen-right-side='true']) {
+      padding-right: 0 !important;
     }
-  }
 
-  .toolbar-items > toolbartabstop:first-child {
-    display: none;
-  }
-
-  #nav-bar > *:not(.titlebar-buttonbox-container) {
-    padding-top: 3px;
-    padding-bottom: 3px;
-  }
-
-  #TabsToolbar-customization-target {
-    height: 100%;
-  }
-
-  #tabbrowser-tabs {
-    margin-inline-start: 0;
-    padding-inline-start: 0;
-    border: none;
-    /*background: light-dark(rgba(0,0,0,.05), rgba(255,255,255,.05));*/
-    margin: 0;
-    border: none;
-    height: 100%;
-
-    border-bottom: 0 !important;
-
-    padding-inline-start: 0 !important;
-    margin-inline-start: 0 !important;
-
-    grid-gap: 0 !important;
-  }
-
-  #tabbrowser-arrowscrollbox {
-    margin-bottom: 3px !important;
-  }
-
-  #alltabs-button stack {
-    transform: rotate(-90deg);
-  }
-
-  .tab-icon-overlay {
-    margin-inline-end: 0 !important;
-    display: none; /* TODO: fix this */
-  }
-
-  .tab-icon-pending {
-    margin-inline-end: 0 !important;
-  }
-
-  @media (-moz-bool-pref: 'zen.view.sidebar-collapsed.hide-mute-button') and (not (-moz-bool-pref: 'zen.view.sidebar-expanded')) {
-    .tab-icon-overlay:is([soundplaying], [muted]):not([selected]) {
-      display: none;
-    }
-  }
-
-  @media (-moz-bool-pref: 'zen.view.sidebar-expanded.on-hover') {
-    :root:not([zen-sidebar-legacy='true']) #navigator-toolbox:is([zen-user-hover='true']:hover, :not([zen-user-hover='true'])) {
-      padding-right: 47px !important;
-    }
-  }
-
-  @media (-moz-bool-pref: 'zen.view.sidebar-expanded') {
-    #navigator-toolbox:is(
-        #navigator-toolbox[zen-user-hover='true']:hover,
-        #navigator-toolbox[zen-user-hover='true']:focus-within,
-        #mainPopupSet[zen-user-hover='true']:has(> #appMenu-popup:hover) ~ toolbox,
-        #navigator-toolbox[zen-user-hover='true']:has(*[open='true']:not(tab):not(#zen-sidepanel-button)),
-        :not([zen-user-hover='true'])
-      ) {
-      --zen-hover-animation: zen-sidebar-panel-animation-2;
-      --zen-navigation-toolbar-min-width: 155px;
-      min-width: var(--zen-navigation-toolbar-min-width) !important;
-      align-items: start;
-      transition: 0.2s;
-      width: 170px;
-      border: none;
-      padding-left: 2px;
-      animation: var(--zen-hover-animation) 0.3s backwards;
-
-      #vertical-pinned-tabs-container {
-        margin-left: var(--zen-tabbrowser-padding);
+    & #vertical-tabs-newtab-button {
+      & label {
+        display: flex;
+        text-align: start;
+        align-items: center;
+        padding: 0;
       }
 
-      #newtab-button-container {
-        margin: calc(var(--zen-tabbrowser-padding) - 2px);
-        margin-bottom: 0;
-
-        & #vertical-tabs-newtab-button {
-          padding: 0 !important;
-        
-          & label {
-            display: flex;
-            text-align: start;
-            align-items: center;
-            padding: 0;
-          }
-        }
-      }
-
-      & .tab-label-container {
-        display: block;
-      }
-
-      & #titlebar,
-      & #TabsToolbar,
-      & #TabsToolbar .toolbar-items {
-        width: 100%;
-        align-items: flex-start;
-      }
-
-      & #TabsToolbar > .toolbar-items toolbarbutton:not(#zen-workspaces-button) {
-        width: 100% !important;
-        border-radius: 8px;
-      }
-
-      & #TabsToolbar > .toolbar-items toolbarbutton:not(#zen-workspaces-button):hover {
-        background: var(--button-hover-bgcolor);
-      }
-
-      & #TabsToolbar > .toolbar-items toolbarbutton:not(#zen-workspaces-button) .toolbarbutton-text,
-      & #TabsToolbar > .toolbar-items toolbarbutton:not(#zen-workspaces-button) .toolbarbutton-icon,
-      & #TabsToolbar > .toolbar-items toolbarbutton:not(#zen-workspaces-button) .toolbarbutton-badge-stack {
+      &:hover * {
         background: transparent !important;
       }
+    }
 
-      & #tabbrowser-arrowscrollbox-periphery > toolbarbutton {
-        display: flex;
-        justify-content: center;
-        align-items: center;
+    @media (-moz-bool-pref: 'zen.view.sidebar-expanded.on-hover') {
+      :root:not([zen-sidebar-legacy='true']) #navigator-toolbox:is([zen-user-hover='true']:hover, :not([zen-user-hover='true'])) {
+        padding-right: 47px !important;
       }
+    }
+  }
 
-      & #tabbrowser-arrowscrollbox .tabbrowser-tab:first-child:not([hidden]) {
-        margin-top: var(--space-small) !important;
-      }
+  /* Mark: toolbox as collapsed */
+  #navigator-toolbox:not(#navigator-toolbox:is(
+    #navigator-toolbox[zen-user-hover='true']:hover,
+    #navigator-toolbox[zen-user-hover='true']:focus-within,
+    #mainPopupSet[zen-user-hover='true']:has(> #appMenu-popup:hover) ~ toolbox,
+    #navigator-toolbox[zen-user-hover='true']:has(*[open='true']:not(tab):not(#zen-sidepanel-button)),
+    #navigator-toolbox[zen-expanded='true']:not([zen-user-hover='true']))) {
+    --zen-toolbox-max-width: 50px;
+    max-width: var(--zen-toolbox-max-width) !important;
+
+    #vertical-tabs-newtab-button {
+      padding: 0 !important;
+      background: transparent !important;
+    }
+
+    & #zen-sidebar-icons-wrapper {
+      display: flex;
+      flex-direction: column;
+      padding-top: calc(var(--zen-toolbox-padding) * 2);
+    }
+
+    :root:has(&) #zen-sidebar-splitter {
+      display: none !important;
+    }
+
+    & #tabbrowser-tabs {
+      --tab-min-width: 36px !important;
 
       & .tabbrowser-tab {
-        max-width: unset !important;
+        margin: 0 auto;
+        width: var(--tab-min-width) !important;
+        height: var(--tab-min-width) !important;
 
-        &:not([pinned]) {
-          width: 100%;
-
-          &:hover .tab-close-button {
-            display: block !important;
-          }
-
-          & .tab-content {
-            position: relative;
-            width: 100%;
-          }
-
-          & .tab-stack {
-            justify-content: start;
-            padding: 10px;
-            width: 100% !important;
-          }
+        & .tab-content {
+          display: flex;
+          align-content: center;
+          justify-content: center;
 
           & .tab-label-container {
-            #tabbrowser-tabs:not([secondarytext-unsupported]) & {
-              display: flex;
-              align-items: center;
-              padding-left: 10px;
-            }
+            display: none;
+          }
+
+          & .tab-icon-image {
+            margin-inline-end: 0 !important;
           }
         }
-
-        &:active,
-        .zen-sidebar-panel-button:active {
-          transform: scale(0.96) !important;
-        }
-
-        &[pinned] {
-          margin: 0 !important;
-        }
-      }
-
-      & #tabbrowser-arrowscrollbox::part(scrollbox) {
-        /* We have the pinned tabs on the top, next to each other,
-        * and the rest of the tabs are below them. */
-        display: grid;
-        grid-template-columns: repeat(auto-fill, minmax(var(--tab-min-height), 1fr));
-        padding: calc(var(--zen-tabbrowser-padding) / 2);
-        padding-right: 0;
-      }
-
-      & .tabbrowser-tab:not([pinned]),
-      & #tabbrowser-arrowscrollbox-periphery {
-        grid-column: 1 / -1;
-      }
-
-      & .tabbrowser-tab[pinned] {
-        grid-column: span 1;
-        min-width: 100%;
-      }
-
-      & #zen-sidebar-icons-wrapper {
-        width: -moz-available;
-        display: grid;
-        grid-template-columns: repeat(auto-fill, minmax(37px, 1fr));
-        transition: 0.1s;
-      }
-
-      & #zen-sidebar-icons-wrapper::before {
-        width: 100%;
       }
     }
   }
 
-  #navigator-toolbox[zen-user-hover='true'] {
-    width: fit-content !important;
-  }
-
-  /* Display the vertical tabs on the right side */
-  @media (-moz-bool-pref: 'zen.tabs.vertical.right-side') and (not (-moz-bool-pref: 'zen.view.compact')) {
-    #navigator-toolbox {
-      order: 8 !important;
-      padding-left: 0 !important;
-      --zen-hover-animation: zen-sidebar-panel-animation-right !important;
-    }
-
-    #tabbrowser-tabpanels {
-      padding-left: var(--zen-element-separation);
-      padding-right: 0 !important;
-    }
-
-    #zen-sidebar-splitter {
-      order: 7 !important;
-    }
-
-    #tabbrowser-tabpanels .browserSidebarContainer {
-      margin-left: 0 !important;
-      margin-right: 2px !important;
-    }
-
-    #tabbrowser-tabs {
-      padding-right: var(--zen-tabbrowser-padding);
-    }
-  }
-
-  @media not (-moz-bool-pref: 'zen.view.sidebar-expanded') {
-    #navigator-toolbox {
-      width: fit-content !important;
-    }
-
-    #tabbrowser-tabs {
-      padding-right: 0 !important;
-    }
+  /* Mark: Separator styling */
+  #zen-sidebar-splitter {
+    opacity: 0;
+    width: var(--zen-toolbox-padding);
+    height: 100%;
   }
 
+  /* Mark: Expand on hover */
   @media (-moz-bool-pref: 'zen.view.sidebar-expanded.on-hover') and (not (-moz-bool-pref: 'zen.view.compact')) {
     #zen-sidebar-splitter {
       display: none !important;
@@ -515,6 +228,7 @@
     #navigator-toolbox:has(.tabbrowser-tab:active),
     #navigator-toolbox:has(*[open='true']:not(tab):not(#zen-sidepanel-button)) {
       --zen-navigation-toolbar-min-width: 3.3rem !important;
+      padding: 0 !important;
 
       & #TabsToolbar {
         z-index: 100 !important;
@@ -522,8 +236,8 @@
         background-color: var(--zen-dialog-background);
         border-top-color: var(--zen-colors-border);
         border-right-color: var(--zen-colors-border);
-        padding-right: 0.1rem !important;
         position: absolute;
+        padding: var(--zen-toolbox-padding);
       }
 
       #navigator-toolbox:not(&)
@@ -536,19 +250,21 @@
         visibility: hidden !important;
       }
 
-      & #tabbrowser-tabs {
-        --zen-tabbrowser-tabs-on-hover-padding: var(--zen-tabbrowser-padding);
-        padding: var(--zen-tabbrowser-tabs-on-hover-padding) !important;
-      }
-
       & #zen-sidebar-icons-wrapper {
         display: block !important;
       }
 
       & .zen-sidebar-action-button {
         width: 100%;
+        border-radius: var(--zen-button-border-radius);
 
-        & > * {
+        &:hover {
+          background: var(--button-hover-bgcolor);
+        }
+
+        & > *,
+        &:hover > * {
+          background: transparent !important;
           --toolbarbutton-active-background: transparent;
         }
 
@@ -559,37 +275,5 @@
         }
       }
     }
-
-    @media (-moz-bool-pref: 'zen.tabs.vertical.right-side') {
-      #TabsToolbar {
-        border-right: 0 !important;
-        border-left: 1px solid transparent;
-        border-top-right-radius: 0;
-        border-top-left-radius: var(--zen-border-radius);
-
-        right: 0;
-      }
-
-      #navigator-toolbox:hover,
-      #navigator-toolbox:focus-within,
-      #navigator-toolbox[movingtab],
-      #mainPopupSet:has(> #appMenu-popup:hover) ~ toolbox,
-      #navigator-toolbox:has(.tabbrowser-tab:active),
-      #navigator-toolbox:has(*[open='true']:not(tab):not(#zen-sidepanel-button)) {
-        --zen-navigation-toolbar-min-width: 0 !important;
-        position: relative;
-        padding: 0 !important;
-
-        & #TabsToolbar {
-          border-left: 1px solid var(--zen-colors-border);
-        }
-      }
-    }
-
-    @media not (-moz-bool-pref: 'zen.tabs.vertical.right-side') {
-      #tabbrowser-tabs {
-        --zen-tabbrowser-tabs-on-hover-padding: 0 var(--zen-tabbrowser-padding) 0 0 !important;
-      }
-    }
   }
-}
+}
\ No newline at end of file
diff --git a/src/browser/base/content/zen-styles/zen-theme.css b/src/browser/base/content/zen-styles/zen-theme.css
index dec76db5e..6724540f2 100644
--- a/src/browser/base/content/zen-styles/zen-theme.css
+++ b/src/browser/base/content/zen-styles/zen-theme.css
@@ -74,8 +74,6 @@
   --zen-button-border-radius: 7px;
   --zen-button-padding: 0.6rem 1.2rem;
 
-  --zen-tabbrowser-padding: 5px;
-
   /* Other colors */
   --urlbar-box-bgcolor: var(--zen-urlbar-background) !important;
   --toolbar-field-focus-background-color: var(--urlbar-box-bgcolor) !important;
diff --git a/src/browser/base/content/zen-styles/zen-workspaces.css b/src/browser/base/content/zen-styles/zen-workspaces.css
index 6f66bb81a..3eb988f52 100644
--- a/src/browser/base/content/zen-styles/zen-workspaces.css
+++ b/src/browser/base/content/zen-styles/zen-workspaces.css
@@ -1,18 +1,11 @@
 #zen-workspaces-button {
-  --zen-workspaces-button-vmargin: 0.4rem;
   border: 1px solid var(--zen-colors-border);
   border-radius: var(--zen-button-border-radius);
-  width: calc(var(--zen-sidebar-action-button-width) - 5px) !important;
-  height: calc(var(--zen-sidebar-action-button-width) - 5px) !important;
-  margin-bottom: var(--zen-workspaces-button-vmargin) !important;
+  min-height: 33px;
   justify-content: center;
   align-items: center;
   display: flex;
   box-shadow: rgba(0, 0, 0, 0.05) 0px 1px 2px 0px;
-
-  :root[zen-sidebar-legacy='true'] & {
-    margin-top: 0 !important;
-  }
 }
 
 #zen-workspaces-button .zen-workspace-sidebar-name {
diff --git a/src/browser/themes/shared/zen-icons/icons.css b/src/browser/themes/shared/zen-icons/icons.css
index ff19c6952..f06f81896 100644
--- a/src/browser/themes/shared/zen-icons/icons.css
+++ b/src/browser/themes/shared/zen-icons/icons.css
@@ -138,6 +138,7 @@
 #appMenu-history-button,
 #appMenu-library-history-button,
 #sidebar-switcher-history,
+#zen-history-button,
 #sidebar-box[sidebarcommand='viewHistorySidebar'] > #sidebar-header > #sidebar-switcher-target > #sidebar-icon {
   list-style-image: url('history.svg') !important;
 }
@@ -219,6 +220,7 @@
 }
 
 #preferences-button,
+#zen-preferences-button,
 .search-setting-button > .button-box > .button-icon,
 #appMenu-settings-button,
 #PanelUI-zen-profiles-managePrfs,
@@ -405,7 +407,8 @@
 }
 
 #pageAction-panel-bookmark,
-#star-button {
+#star-button,
+#zen-bookmark-button {
   list-style-image: url('bookmark-hollow.svg') !important;
 }