diff --git a/css/leptonChrome.css b/css/leptonChrome.css
index 472e08d..1eadb74 100644
--- a/css/leptonChrome.css
+++ b/css/leptonChrome.css
@@ -9124,7 +9124,7 @@
 @supports -moz-bool-pref("userChrome.sidebar.overlap") or -moz-bool-pref("userChrome.autohide.sidebar") {
   #sidebar-box {
     --uc-sidebar-shadow-color: #28282f;
-    z-index: 1 !important;
+    z-index: var(--browser-area-z-index-sidebar-splitter, 3) !important;
     position: relative !important;
     box-shadow: var(--uc-sidebar-shadow-position) 0px 15px -10px var(--uc-sidebar-shadow-color);
   }
@@ -23790,7 +23790,7 @@
 @media (-moz-bool-pref: "userChrome.sidebar.overlap"), (-moz-bool-pref: "userChrome.autohide.sidebar") {
   #sidebar-box {
     --uc-sidebar-shadow-color: #28282f;
-    z-index: 1 !important;
+    z-index: var(--browser-area-z-index-sidebar-splitter, 3) !important;
     position: relative !important;
     box-shadow: var(--uc-sidebar-shadow-position) 0px 15px -10px var(--uc-sidebar-shadow-color);
   }
diff --git a/css/leptonChromeESR.css b/css/leptonChromeESR.css
index 8fb0f57..e3e63a9 100644
--- a/css/leptonChromeESR.css
+++ b/css/leptonChromeESR.css
@@ -9554,7 +9554,7 @@
 @supports -moz-bool-pref("userChrome.sidebar.overlap") or -moz-bool-pref("userChrome.autohide.sidebar") {
   #sidebar-box {
     --uc-sidebar-shadow-color: #28282f;
-    z-index: 1 !important;
+    z-index: var(--browser-area-z-index-sidebar-splitter, 3) !important;
     position: relative !important;
     box-shadow: var(--uc-sidebar-shadow-position) 0px 15px -10px var(--uc-sidebar-shadow-color);
   }
diff --git a/src/sidebar/_overlap.scss b/src/sidebar/_overlap.scss
index b1f1585..77e0655 100644
--- a/src/sidebar/_overlap.scss
+++ b/src/sidebar/_overlap.scss
@@ -33,7 +33,7 @@
   #sidebar-box {
     --uc-sidebar-shadow-color: #28282F;
 
-    z-index: 1 !important;
+    z-index: var(--browser-area-z-index-sidebar-splitter, 3) !important;
     position: relative !important;
 
     box-shadow: var(--uc-sidebar-shadow-position) 0px 15px -10px var(--uc-sidebar-shadow-color);