[nautilus/2161-laggy-scrolling-with-adwaita-theme: 3/4] css: Don't use shadow bur for thumbnails

[António Fernandes <antoniof src gnome org>]

commit 82f04f12f89071340ff31a864804280bf31d3eed
Author: António Fernandes <antoniof gnome org>
Date:   Mon Feb 28 14:30:42 2022 +0000

    css: Don't use shadow bur for thumbnails
    
    Gaussian blur has high performance impact.
    
    Overlap plain shadows with varying offsets and opacity to achieve an
    identical visual result at low performance cost.
    
    Fixes https://gitlab.gnome.org/GNOME/nautilus/-/issues/2161

 src/resources/css/Adwaita.css | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)
---
diff --git a/src/resources/css/Adwaita.css b/src/resources/css/Adwaita.css
index 4991979cf..1135871be 100644
--- a/src/resources/css/Adwaita.css
+++ b/src/resources/css/Adwaita.css
@@ -13,10 +13,12 @@
 }
 
 .nautilus-canvas-item.thumbnail {
-  -gtk-icon-shadow: 0px 1px 2px @borders,
-                    1px 0px 0px alpha(@borders, 0.25),
-                    -1px 0px 0px alpha(@borders, 0.25),
-                    0px 2px 0px alpha(@borders, 0.5);
+  -gtk-icon-shadow:  0px -1px  alpha(@borders, 0.2),
+                     2px  0px  alpha(@borders, 0.2),
+                    -2px  0px  alpha(@borders, 0.2),
+                     0px  3px  alpha(@borders, 0.2),
+                     1px  2px  alpha(@borders, 0.4),
+                    -1px  2px  alpha(@borders, 0.4);
 }
 
 .nautilus-canvas-item.dim-label {
@@ -195,10 +197,12 @@ entry.search > * {
 }
 
 .nautilus-list-view.thumbnail {
-  -gtk-icon-shadow: 0px 1px 2px @borders,
-                    1px 0px 0px alpha(@borders, 0.25),
-                    -1px 0px 0px alpha(@borders, 0.25),
-                    0px 2px 0px alpha(@borders, 0.5);
+  -gtk-icon-shadow:  0px -1px  alpha(@borders, 0.2),
+                     2px  0px  alpha(@borders, 0.2),
+                    -2px  0px  alpha(@borders, 0.2),
+                     0px  3px  alpha(@borders, 0.2),
+                     1px  2px  alpha(@borders, 0.4),
+                    -1px  2px  alpha(@borders, 0.4);
 }
 
 .search-information {