support new niri features in config

modules/desktop/home/niri/style.nix

@@ -81,6 +81,25 @@
           };
         clip-to-geometry = true;
       }
+      {
+        matches = [ { is-window-cast-target = true; } ];
+        border = {
+          inactive.gradient = {
+            from = "#64de50";
+            to = "#ff9a56";
+            in' = "oklch shorter hue";
+            relative-to = "window";
+            angle = 135;
+          };
+          active.gradient = {
+            from = "#64de50";
+            to = "#5bcefa";
+            in' = "oklch shorter hue";
+            relative-to = "window";
+            angle = 135;
+          };
+        };
+      }
     ];
   };
 }