[gnome-shell-sass] theme: Drop custom assets for window close buttons in overview

[Florian Müllner <fmuellner src gnome org>]

commit 6a8aa1bc8078a20fc7e387bd8eaa47a88c3a6c12
Author: Sam Hewitt <sam snwh org>
Date:   Fri Nov 16 11:15:44 2018 -0500

    theme: Drop custom assets for window close buttons in overview
    
    They can be replaced by a themed icon and some CSS styling.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/issues/782

 _common.scss | 28 ++++++++++++++++++++--------
 1 file changed, 20 insertions(+), 8 deletions(-)
---
diff --git a/_common.scss b/_common.scss
index c905b3b..5282021 100644
--- a/_common.scss
+++ b/_common.scss
@@ -1160,14 +1160,26 @@ StScrollBar {
 //close buttons
 
 .window-close {
-  background-image: url("resource:///org/gnome/shell/theme/close-window.svg");
-  background-size: 32px;
-  height: 32px;
-  width: 32px;
-  -shell-close-overlap: 16px;
-
-  &:hover { background-image: url("resource:///org/gnome/shell/theme/close-window-hover.svg"); }
-  &:active { background-image: url("resource:///org/gnome/shell/theme/close-window-active.svg"); }
+  background-color: white;
+  border-radius: 24px;
+  border: 4px solid $selected_bg_color;
+  box-shadow: inset 0 -4px 0 0 transparentize($selected_bg_color, 0.5);
+  color: $selected_bg_color;
+  height: 24px;
+  width: 24px;
+  -shell-close-overlap: 14px;
+
+  &:hover {
+    background-color: $selected_bg_color;
+    border-color: white;
+    color: white;
+  }
+
+  &:active {
+    background-color: mix(white, $selected_bg_color, 75%);
+    border-color: $selected_bg_color;
+    color: $selected_bg_color;
+  }
 }
 
 /* NETWORK DIALOGS */