<!DOCTYPE HTML>
<html>
<title>Reftest, bug 1156456</title>
<style>

body {
  background: #2a4;
}

@keyframes HoldOpacity {
  from, to {
    opacity: 0.6;
  }
}

div {
  width: 200px; height: 200px;
  background: #c37;
  animation: 10s HoldOpacity infinite;
}

</style>
<div></div>