diff --git a/index.html b/index.html
index a6b3912..07b23d0 100644
--- a/index.html
+++ b/index.html
@@ -78,15 +78,26 @@
         var header = document.getElementById("header");
         var awdog = document.getElementById("awdog");
 
+        var intensity = 0;
+
         function pet() {
-            alert("pet");
+            intensity = 10;
         }
 
+        var prevTime = 0;
+
         async function update(timestamp) {
+            let dt = (timestamp - prevTime) / 1000;
+            prevTime = timestamp;
+
             // petting shake
             let a = Math.random() * Math.PI * 2;
-            let intensity = 20;
             awdog.style.transform = "translate(" + (Math.cos(a) * intensity) + "px, " + (Math.sin(a) * intensity) + "px)";
+            if (intensity > 0) {
+                intensity -= 10 * dt;
+            } else {
+                intensity = 0;
+            }
 
             // header
             let t = timestamp / 500;