<!DOCTYPE html>
<meta charset="UTF-8">
<title>CSS Test: system additive, invalid</title>
<link rel="author" title="Xidorn Quan" href="https://www.upsuper.org/">
<link rel="help" href="https://drafts.csswg.org/css-counter-styles-3/#additive-system">
<link rel="match" href="system-common-invalid-ref.html">
<link rel="stylesheet" href="support/test-common.css">
<style type="text/css">
  @counter-style a {
    system: additive;
    suffix: ":";
  }
</style>
<ol start="-2" style="list-style-type: a">
  <li>foo<li>bar<li>foo<li>bar
</ol>