<!DOCTYPE html>
<meta charset="utf-8">
<title>test reference</title>
<link rel="author" title="Florian Rivoal" href="https://florian.rivoal.net/">
<style>
div {
  font-family: Ahem;
  color: transparent;
  font-size: 50px;
  background: green;
}
</style>

<p>Test passes if there is a green rectangle below and no red.
<div>XS<br>S<br>XS<br>S</div>