[gnome-text-editor] css: tweak border between document and map

[Christian Hergert <chergert src gnome org>]

commit 390e08223f841df744f0eb2d1d2e638636ac9757
Author: Christian Hergert <chergert redhat com>
Date:   Mon Jun 21 21:26:27 2021 -0700

    css: tweak border between document and map

 src/TextEditor.css | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/TextEditor.css b/src/TextEditor.css
index 61cef56..1b9430b 100644
--- a/src/TextEditor.css
+++ b/src/TextEditor.css
@@ -116,8 +116,8 @@ notebook:focus:backdrop {
 }
 
 textview.source-map:dir(ltr) {
-  border-left: 1px solid @borders;
+  border-left: 1px solid alpha(@borders,.3);
 }
 textview.source-map:dir(rtl) {
-  border-right: 1px solid @borders;
+  border-right: 1px solid alpha(@borders,.3);
 }