[sysprof] theme: use box-shadow

[Christian Hergert <chergert src gnome org>]

commit 565b6ec56605c30030636d1d168f6820639ca905
Author: Christian Hergert <chergert redhat com>
Date:   Fri Jun 14 17:47:25 2019 -0700

    theme: use box-shadow

 src/libsysprof-ui/css/SysprofVisualizerView-shared.css | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/libsysprof-ui/css/SysprofVisualizerView-shared.css 
b/src/libsysprof-ui/css/SysprofVisualizerView-shared.css
index 0fd2f82..bc0fca4 100644
--- a/src/libsysprof-ui/css/SysprofVisualizerView-shared.css
+++ b/src/libsysprof-ui/css/SysprofVisualizerView-shared.css
@@ -1,7 +1,7 @@
 visualizers.selection {
   background: none;
   background-color: alpha(@theme_selected_bg_color, 0.35);
-  border: 1px solid @theme_selected_bg_color;
+  box-shadow: 0 0 0 1px @theme_selected_bg_color inset;
 }
 visualizers.selection:backdrop {
   background: none;