<!DOCTYPE html>
<html>
<style>
body {
  margin: 0px;
}
span {
  color: green;
  font-family: Ahem;
  font-size: 20px;
}
</style>
<body>
<span id=changeThis>PASS if you cannot read this text.</span><script>
document.body.offsetHeight;
changeThis.style.backgroundColor = "green";
</script></body></html>