[gnome-shell] theme: Provide icon helper classes

[Jakub Steiner <jimmac src gnome org>]

commit 043667dde571bfb11fff307bbf8bc5d2b8a72e5a
Author: Jakub Steiner <jimmac gmail com>
Date:   Tue Jul 16 00:04:48 2019 +0200

    theme: Provide icon helper classes
    
    - to help present icons on light backgrounds, the new fullcolor
      icons need some help. Mimic gtk styles
    
    Needed for https://gitlab.gnome.org/GNOME/gnome-shell-extensions/issues/168

 data/theme/gnome-shell-sass/_common.scss | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
---
diff --git a/data/theme/gnome-shell-sass/_common.scss b/data/theme/gnome-shell-sass/_common.scss
index 7e3f513ec..ae1bed6a7 100644
--- a/data/theme/gnome-shell-sass/_common.scss
+++ b/data/theme/gnome-shell-sass/_common.scss
@@ -619,6 +619,22 @@ StScrollBar {
   app menu inside the main app window itself rather than the top bar
 */
 
+/*************
+ * App Icons *
+ *************/
+/* Outline for low res icons */
+.lowres-icon {
+    icon-shadow: 0 -1px rgba(0,0,0,0.05),
+      1px 0 rgba(0,0,0,0.1),
+      0 1px rgba(0,0,0,0.3),
+      -1px 0 rgba(0,0,0,0.1);
+}
+
+/* Drapshadow for large icons */
+.icon-dropshadow {
+  icon-shadow: 0 2px 12px rgba(0,0,0,0.1),
+               0 1px 2px rgba(0,0,0,0.5);
+}
 
 /* OSD */
 .osd-window {