[gnome-builder/wip/chergert/completion] style: tweak styling for completion window

[Christian Hergert <chergert src gnome org>]

commit 197530ab8350551e141a57643a57398c1410fd09
Author: Christian Hergert <chergert redhat com>
Date:   Sat Jun 2 15:14:52 2018 -0700

    style: tweak styling for completion window
    
    This makes things a bit more contrasting when on dark themes.

 data/themes/shared/shared-completion.css | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)
---
diff --git a/data/themes/shared/shared-completion.css b/data/themes/shared/shared-completion.css
index 899dcdc8c..6c8a5b269 100644
--- a/data/themes/shared/shared-completion.css
+++ b/data/themes/shared/shared-completion.css
@@ -9,12 +9,21 @@ completionview > * {
   border: 1px solid @borders;
   box-shadow: 0px 0px 3px @wm_shadow;
   padding: 0px 3px 0px 3px;
-  background: @content_view_bg;
+  /* on light themes, this won't really do much, but for
+   * dark themes, it gives us some contrast from dark backgrounds
+   * such as the builder-dark theme.
+   */
+  background-color: shade(@content_view_bg, 1.5);
   border-radius: 5px;
 }
 
 completionview list {
   padding: 3px 0 3px 0;
+  background-color: transparent;
+}
+
+completionview list row:not(:selected) {
+  background-color: transparent;
 }
 
 completionview list row {