[gnome-games/wip/exalm/libhandy4: 4/19] ui: Add css from libhandy example

[Alexander Mikhaylenko <alexm src gnome org>]

commit 929fb283baf5ad342c59f9f46551c1076d006f0e
Author: Alexander Mikhaylenko <exalm7659 gmail com>
Date:   Wed Sep 12 14:29:52 2018 +0500

    ui: Add css from libhandy example

 data/gtk-style.css | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)
---
diff --git a/data/gtk-style.css b/data/gtk-style.css
index f7b2a5ee..2474ae3c 100644
--- a/data/gtk-style.css
+++ b/data/gtk-style.css
@@ -25,3 +25,40 @@ gamesgamethumbnail {
 .devel headerbar label {
        color: @theme_fg_color;
 }
+
+/* Styles from libhandy example, this should be kept in sync with this:
+ * https://source.puri.sm/Librem5/libhandy/blob/master/examples/style.css
+ */
+
+stacksidebar list {
+       border-left-width: 0px;
+       border-right-width: 0px;
+}
+
+/* Needed for separators to look good. These have been submitted upstream here:
+ * https://gitlab.gnome.org/GNOME/gtk/merge_requests/323
+ */
+
+separator.sidebar {
+       background-color: @borders;
+       border-style: none;
+       margin: 0px 0px 0px 0px;
+}
+
+separator.sidebar:backdrop {
+       background-color: @unfocused_borders;
+}
+
+separator.sidebar.selection-mode,
+.selection-mode separator.sidebar {
+       background-color: mix(@theme_selected_bg_color, #000, 0.2);
+}
+
+/* Needed for HdyTitleBar to work. This has been merged upstream but no release
+ * include it yet, it is likely to be released as part of GTK+ 3.24.1.
+ */
+headerbar.titlebar headerbar:not(.titlebar) {
+       background-color: rgba (0, 0, 0, 0);
+       background-image: none;
+       box-shadow: none;
+}