diff --git a/rtdata/themes/RawTherapee-GTK3-20_.css b/rtdata/themes/RawTherapee-GTK3-20_.css
index a343dd9fb..27d2b5f13 100644
--- a/rtdata/themes/RawTherapee-GTK3-20_.css
+++ b/rtdata/themes/RawTherapee-GTK3-20_.css
@@ -70,7 +70,10 @@ headerbar {
     border-radius: 5px 5px 0 0;
     min-height: 26px;
     padding: 1px 5px 0;
-    margin: 0 0 1px 0;
+    margin: 0;
+}
+.csd #MainNotebook > header.top {
+    border-top: 1px solid #484848;
 }
 
 /* Window state */