[gthumb] css: fixed invisible hightlighted text when the window is unfocused

[Paolo Bacchilega <paobac src gnome org>]

commit 79c1bbff68f9eb2614194b8572dc4af2d0fff37c
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Wed Jun 2 12:33:20 2021 +0200

    css: fixed invisible hightlighted text when the window is unfocused
    
    Use a darker variant of the theme color instead of a
    fixed value.

 gthumb/resources/gthumb.css | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/gthumb/resources/gthumb.css b/gthumb/resources/gthumb.css
index 36c29b01..0c26dcf8 100644
--- a/gthumb/resources/gthumb.css
+++ b/gthumb/resources/gthumb.css
@@ -124,7 +124,7 @@ GtkScrolledWindow.comment.undershoot {
 }
 
 .highlighted-text:backdrop {
-       color: #333333;
+       color: darker(currentColor);
 }
 
 /* -- extension list in the preferences dialog -- */