css/css-conditional/at-supports-040.html

<!doctype html>
<title>CSS Conditional Test: @supports selector() with pseudo-elements.</title>
<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io">
<link rel="author" href="https://mozilla.org" title="Mozilla">
<link rel="help" href="https://drafts.csswg.org/css-conditional/#at-supports">
<link rel="match" href="at-supports-001-ref.html">
<style>
  div {
    background-color:red;
    height:100px;
    width:100px;
  }
  @supports selector(::before) {
    div { background: green };
  }
</style>
<p>Test passes if there is a <strong>filled green square</strong> and <strong>no red</strong>.</p>
<div></div>