<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS Containment Test: Reference file</title>
<link rel="author" title="Manuel Rego Casasnovas" href="mailto:rego@igalia.com">
<style>
button {
  border: 5px solid green;
  padding: 0;
  color: transparent;
  width: 0;
  height: 0;
  font-size: 2em;
}
</style>

<p>This test passes if it has the same output as the reference. You see the word "before", a 10px green square at the top, and then the word "after".</p>
before<button>b</button>after