chore(ui): tweak toast background

demo/karma.yaml

@@ -24,6 +24,11 @@ alertmanager:
       proxy: true
       cors:
         credentials: same-origin
+      healthcheck:
+        filters:
+          DeadMansSwitch:
+            - alertname=Random Instances
+            - instance=server30
 
 alertAcknowledgement:
   enabled: true

ui/src/Styles/Components/Toast.scss

@@ -21,7 +21,13 @@
 }
 
 .bg-toast {
-  background-color: darken($dark, 5%);
+  @supports (backdrop-filter: blur(1px)) {
+    background-color: rgba(darken($dark, 5%), 0.85);
+    backdrop-filter: saturate(50%) blur(6px);
+  }
+  @supports not (backdrop-filter: blur(1px)) {
+    background-color: darken($dark, 5%);
+  }
 }
 
 .toast-upgrade-progressbar {