<!doctype html>
<html>
  <head>
    <title>CSS Test (Conditional Rules): In @supports, ::details-content::before can be parsed successfully</title>
    <link rel="author" title="Luke Warlow" href="mailto:lwarlow@igalia.com">
    <link rel="help" href="https://drafts.csswg.org/css-conditional-3/#at-supports">
    <link rel="help" href="https://drafts.csswg.org/css-pseudo-4/#details-content-pseudo">
    <link rel="match" href="at-supports-001-ref.html">
    <style>
      div {
        background: red;
       