Merge lp:~3v1n0/ubuntu-themes/backdrop-links-opacity into lp:ubuntu-themes

[Marco Trevisan (Treviño)]

Ambiance, Radiance: add some transparency to links color when in backdrop

=== modified file 'Ambiance/gtk-3.20/gtk-widgets.css'
--- Ambiance/gtk-3.20/gtk-widgets.css	2018-03-28 06:27:00 +0000
+++ Ambiance/gtk-3.20/gtk-widgets.css	2018-04-10 22:18:14 +0000
@@ -3809,3 +3809,8 @@
 *:visited {
     color: @link_color;
 }
+
+*:link:backdrop,
+*:visited:backdrop {
+    opacity: 0.8;
+}
 
=== modified file 'Radiance/gtk-3.20/gtk-widgets.css'
--- Radiance/gtk-3.20/gtk-widgets.css	2018-03-28 06:27:00 +0000
+++ Radiance/gtk-3.20/gtk-widgets.css	2018-04-10 22:18:14 +0000
@@ -3799,3 +3799,8 @@
 *:visited {
     color: @link_color;
 }
+
+*:link:backdrop,
+*:visited:backdrop {
+    opacity: 0.8;
+}