diff --git a/gtk/theme/Adwaita/_common.scss b/gtk/theme/Adwaita/_common.scss
index 1cb2c7da66..d5117f2b08 100644
--- a/gtk/theme/Adwaita/_common.scss
+++ b/gtk/theme/Adwaita/_common.scss
@@ -3942,7 +3942,7 @@ filechooserbutton:drop(active) {
       border-left-style: none;
     }
 
-    @at-root %sidebar_right
+    @at-root %sidebar_right,
     &:dir(rtl),
     &.right {
       border-left: 1px solid $borders_color;
diff --git a/gtk/theme/Adwaita/gtk-contained-dark.css b/gtk/theme/Adwaita/gtk-contained-dark.css
index c2d39a52c9..d8ebd38aad 100644
--- a/gtk/theme/Adwaita/gtk-contained-dark.css
+++ b/gtk/theme/Adwaita/gtk-contained-dark.css
@@ -1659,7 +1659,7 @@ filechooserbutton:drop(active) { box-shadow: none; border-color: transparent; }
 
 stacksidebar.sidebar:dir(ltr) list, stacksidebar.sidebar.left list, stacksidebar.sidebar.left:dir(rtl) list, .sidebar:not(separator):dir(ltr), .sidebar:not(separator).left, .sidebar:not(separator).left:dir(rtl) { border-right: 1px solid #1b1b1b; border-left-style: none; }
 
-stacksidebar.sidebar:dir(rtl) list .sidebar:not(separator):dir(rtl), stacksidebar.sidebar.right list .sidebar:not(separator):dir(rtl), .sidebar:not(separator).right { border-left: 1px solid #1b1b1b; border-right-style: none; }
+stacksidebar.sidebar:dir(rtl) list, stacksidebar.sidebar.right list, .sidebar:not(separator):dir(rtl), .sidebar:not(separator).right { border-left: 1px solid #1b1b1b; border-right-style: none; }
 
 .sidebar:backdrop { background-color: #323232; border-color: #202020; transition: 200ms ease-out; }
 
diff --git a/gtk/theme/Adwaita/gtk-contained.css b/gtk/theme/Adwaita/gtk-contained.css
index 1b20d3812f..8531dec288 100644
--- a/gtk/theme/Adwaita/gtk-contained.css
+++ b/gtk/theme/Adwaita/gtk-contained.css
@@ -1679,7 +1679,7 @@ filechooserbutton:drop(active) { box-shadow: none; border-color: transparent; }
 
 stacksidebar.sidebar:dir(ltr) list, stacksidebar.sidebar.left list, stacksidebar.sidebar.left:dir(rtl) list, .sidebar:not(separator):dir(ltr), .sidebar:not(separator).left, .sidebar:not(separator).left:dir(rtl) { border-right: 1px solid #cdc7c2; border-left-style: none; }
 
-stacksidebar.sidebar:dir(rtl) list .sidebar:not(separator):dir(rtl), stacksidebar.sidebar.right list .sidebar:not(separator):dir(rtl), .sidebar:not(separator).right { border-left: 1px solid #cdc7c2; border-right-style: none; }
+stacksidebar.sidebar:dir(rtl) list, stacksidebar.sidebar.right list, .sidebar:not(separator):dir(rtl), .sidebar:not(separator).right { border-left: 1px solid #cdc7c2; border-right-style: none; }
 
 .sidebar:backdrop { background-color: #f9f9f8; border-color: #d5d0cc; transition: 200ms ease-out; }