diff --git a/chrome/global/browser.css b/chrome/global/browser.css
index 962d78a..f294952 100644
--- a/chrome/global/browser.css
+++ b/chrome/global/browser.css
@@ -13,15 +13,62 @@
 }
 
 @media (-moz-bool-pref: "uc.tweak.rounded-corners") {
-  :root #browser>#appcontent {
-    margin: 0px 3px 3px 3px;
-    border-radius: 8px;
+  /* Fix changes to the bookmarks bar made in Firefox 120 */
+  :root[BookmarksToolbarOverlapsBrowser] .newTabBrowserPanel {
+    padding-top: 0 !important;
+  }
+
+  :root[BookmarksToolbarOverlapsBrowser] #appcontent {
+    margin-top: var(--bookmarks-toolbar-overlapping-browser-height);
+  }
+
+  :root {
+    --uc-tweak-rounded-corners-padding: 3px;
+    --uc-tweak-rounded-corners-border: 1px;
+    --uc-tweak-rounded-corners-radius: 8px;
+
+    & #browser:not([style*="--sidebar-border-color"]) {
+      --sidebar-border-color: light-dark(#bfbfbf80, #595959) !important;
+    }
+  }
+
+  /* disable rounded corners in fullscreen, only if the toolbar is hidden */
+  :root[inFullscreen] #navigator-toolbox:where([style*="margin-top"], [fullscreenShouldAnimate]) + #browser {
+    --uc-tweak-rounded-corners-padding: 0;
+    --uc-tweak-rounded-corners-border: 0;
+    --uc-tweak-rounded-corners-radius: 0;
+  }
+
+  #appcontent {
+    margin-inline: var(--uc-tweak-rounded-corners-padding);
+    margin-block-end: var(--uc-tweak-rounded-corners-padding);
+    border-radius: var(--uc-tweak-rounded-corners-radius);
     overflow: hidden;
-    border: 1.25px solid rgb(0 0 0 / .05);
+    border: 1px solid rgb(0 0 0 / .1);
     box-shadow: 0px 1px 2px rgb(0 0 0 / .1);
   }
-  
-  :root #browser {
+
+
+  /* apply rounded corners to sidebar */
+  #sidebar-box {
+    margin-inline-start: var(--uc-tweak-rounded-corners-padding) !important;
+    margin-block-end: var(--uc-tweak-rounded-corners-padding) !important;
+    border-radius: var(--uc-tweak-rounded-corners-radius) !important;
+    overflow: hidden !important;
+    border: 1px solid rgb(0 0 0 / .1);
+    
+    &[positionend] {
+      margin-inline-start: 0 !important;
+      margin-inline-end: var(--uc-tweak-rounded-corners-padding) !important;
+    }
+  }
+
+  /* remove sidebar border */
+  #sidebar-splitter {
+    border-inline-width: 0 !important;
+  }
+
+  #browser {
     background-color: var(--browser-frame-bgcolor);
   }
 }
diff --git a/chrome/global/colors.css b/chrome/global/colors.css
index 68bd0a5..f775789 100644
--- a/chrome/global/colors.css
+++ b/chrome/global/colors.css
@@ -68,6 +68,7 @@
   --uc-private-browsing-indicator-text: var(--button-primary-color);
   --tab-icon-overlay-stroke: light-dark(#fff, #4b4b4b) !important;
   --tab-icon-overlay-fill: light-dark(#252525, #fff) !important;
+  --toolbarseparator-color: color-mix(in srgb, currentColor 40%, transparent) !important;
 }
 
 /* ensure that dark mode is enabled completely in private browsing mode. */
diff --git a/chrome/global/popup.css b/chrome/global/popup.css
index 20f055b..04e1409 100644
--- a/chrome/global/popup.css
+++ b/chrome/global/popup.css
@@ -403,7 +403,7 @@ panelview .toolbarbutton-1,
   panel[type="autocomplete-richlistbox"]>.autocomplete-richlistbox,
   .menupopup-arrowscrollbox {
     background: var(--arrowpanel-background) !important;
-    border: 0 !important;
+    border: 1px solid var(--panel-separator-color) !important;
   }
 
   /* make room for menu shadow */
@@ -493,6 +493,10 @@ panelview .toolbarbutton-1,
     padding: 0 !important;
     background: none !important;
     border-top: 1px solid var(--panel-separator-color) !important;
+
+    &::before {
+      content: unset !important;
+    }
   }
 
   #PlacesToolbar menupopup[placespopup="true"] menuseparator::before {
diff --git a/chrome/toolbar/personalbar.css b/chrome/toolbar/personalbar.css
index 0051896..0215c1c 100644
--- a/chrome/toolbar/personalbar.css
+++ b/chrome/toolbar/personalbar.css
@@ -4,39 +4,60 @@
   --bookmark-block-padding: 6px !important;
 }
 
+/* Bookmarks bar item sizing */
 #personal-toolbar-empty-description,
 #PersonalToolbar .toolbarbutton-1,
 toolbarbutton.bookmark-item:not(.subviewbutton) {
-  margin-block: 0 4px !important;
-  padding: var(--bookmark-block-padding) 6px !important;
+  margin-block: 2px 4px !important;
+  padding-block: var(--bookmark-block-padding) !important;
+  padding-inline: 6px !important;
   font-size: 12px !important;
+
+  /* Adjust vertical label position on Windows */
+  @media (-moz-platform: windows) {
+    & .toolbarbutton-text {
+      margin-block: -1px 0 !important;
+    }
+  }
 }
 
 #PersonalToolbar .toolbarbutton-1 {
   padding: 0 !important;
 }
 
-#PlacesToolbarItems>toolbarseparator::before {
-  content: "";
-  display: block;
-  border-inline-start: 1px solid var(--toolbarseparator-color) !important;
-  margin-block: 6px 10px !important;
-  border-image-source: none !important;
+/* Bookmarks bar separators */
+#PlacesToolbarItems > toolbarseparator {
+  padding-inline: 1px !important;
+
+  &::before {
+    content: "";
+    display: block;
+    border-inline-start: 1px solid var(--toolbarseparator-color) !important;
+    margin-block: 8px 10px !important;
+    border-image-source: none !important;
+  }
 }
 
+/* Left and Right padding of bookmarks bar */
 #PersonalToolbar {
   padding-inline: calc(var(--toolbar-start-end-padding) - 2px) calc(var(--toolbar-start-end-padding) + 6px) !important;
 }
 
+/* Spacing between icon and label for bookmarks bar items */
 #managed-bookmarks>.toolbarbutton-icon,
 #bookmarks-toolbar-placeholder>.toolbarbutton-icon,
 #PlacesToolbarItems>.bookmark-item>.toolbarbutton-icon[label]:not([label=""]),
 #OtherBookmarks.bookmark-item[container]>.toolbarbutton-icon {
-  margin-inline-end: 6px !important;
+  margin-inline-end: 8px !important;
 }
 
+/* Sizing for bookmarks bar icons */
 #PersonalToolbar .toolbarbutton-1>.toolbarbutton-icon {
   width: calc(2 * var(--bookmark-block-padding) + 16px) !important;
   height: calc(2 * var(--bookmark-block-padding) + 16px) !important;
   padding: var(--bookmark-block-padding) !important;
 }
+
+:root {
+  --bookmarks-toolbar-overlapping-browser-height: 34px !important;
+}
diff --git a/chrome/toolbar/tabbar.css b/chrome/toolbar/tabbar.css
index 781cf66..282d1ac 100644
--- a/chrome/toolbar/tabbar.css
+++ b/chrome/toolbar/tabbar.css
@@ -265,13 +265,15 @@
   padding: 0 12px !important;
 }
 
-.tabbrowser-tab[usercontextid]>.tab-stack>.tab-background>.tab-context-line {
-  height: 8px !important;
-  clip-path: inset(0 0 6px) !important;
-  border-radius: var(--tab-border-radius) !important;
-  border-bottom-left-radius: 0 !important;
-  border-bottom-right-radius: 0 !important;
-  margin: 0 !important;
+/* Tab container indicator */
+.tabbrowser-tab[usercontextid] .tab-background .tab-context-line {
+  height: 2px !important;
+  border-radius: 2px !important;
+  margin: 2px 7px 0 !important;
+}
+
+.tabbrowser-tab[selected][usercontextid] .tab-background .tab-context-line {
+  margin-inline: 9px !important;
 }
 
 .titlebar-spacer[type="post-tabs"] {