diff --git a/pkg/emscripten/proto.css b/pkg/emscripten/proto.css
index 596017e3cd..bd58c5148b 100644
--- a/pkg/emscripten/proto.css
+++ b/pkg/emscripten/proto.css
@@ -16,11 +16,34 @@
  */
 .webplayer-preview {
   cursor: wait;
-  opacity: 0.3;
+  opacity: 0.2;
+  transition: all 0.8s;
+  -webkit-animation: loading 0.8s ease-in-out infinite alternate;
+  -moz-animation: loading 0.8s ease-in-out infinite alternate;
+  animation: loading 0.8s ease-in-out infinite alternate;
 }
 .webplayer-preview.loaded {
   cursor: pointer;
   opacity: 1;
+  -webkit-animation: loaded 0.8s ease-in-out;
+  -moz-animation: loaded 0.8s ease-in-out;
+  animation: loaded 0.8s ease-in-out;
+}
+@-webkit-keyframes loaded {
+  from {
+    opacity: 0.2;
+  }
+  to {
+    opacity: 1;
+  }
+}
+@-webkit-keyframes loading {
+  from {
+    opacity: 0.2;
+  }
+  to {
+    opacity: 0.35;
+  }
 }
 
 /**
@@ -55,4 +78,4 @@ textarea {
     border-color: transparent; 
     overflow: auto;
     resize: none;
-}
\ No newline at end of file
+}