diff --git a/gtk/theme/Adwaita/_common.scss b/gtk/theme/Adwaita/_common.scss
index ebae7d25d3..15a228e0b6 100644
--- a/gtk/theme/Adwaita/_common.scss
+++ b/gtk/theme/Adwaita/_common.scss
@@ -3595,6 +3595,10 @@ separator {
   background: transparentize(black, 0.9);
   min-width: 1px;
   min-height: 1px;
+
+  &.selection-mode {
+    background-color: darken($selected_bg_color, 20%);
+  }
 }
 
 
diff --git a/gtk/theme/Adwaita/gtk-contained-dark.css b/gtk/theme/Adwaita/gtk-contained-dark.css
index b490fdb614..32ea468f42 100644
--- a/gtk/theme/Adwaita/gtk-contained-dark.css
+++ b/gtk/theme/Adwaita/gtk-contained-dark.css
@@ -1563,6 +1563,8 @@ scrolledwindow junction:backdrop { border-image-source: linear-gradient(to botto
 
 separator { background: rgba(0, 0, 0, 0.1); min-width: 1px; min-height: 1px; }
 
+separator.selection-mode { background-color: #0f2b48; }
+
 /********* Lists * */
 list { color: white; background-color: #232729; border-color: #1b1f20; }
 
diff --git a/gtk/theme/Adwaita/gtk-contained.css b/gtk/theme/Adwaita/gtk-contained.css
index 66e888bd56..1126820c01 100644
--- a/gtk/theme/Adwaita/gtk-contained.css
+++ b/gtk/theme/Adwaita/gtk-contained.css
@@ -1583,6 +1583,8 @@ scrolledwindow junction:backdrop { border-image-source: linear-gradient(to botto
 
 separator { background: rgba(0, 0, 0, 0.1); min-width: 1px; min-height: 1px; }
 
+separator.selection-mode { background-color: #215d9c; }
+
 /********* Lists * */
 list { color: black; background-color: #ffffff; border-color: #b6b6b3; }