css/css-cascade/layer-stylesheet-sharing.html

<!doctype html>
<title>Test anonymous layers with stylesheet sharing</title>
<link rel="help" href="https://drafts.csswg.org/css-cascade-5/#layering">
<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1730123">
<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io">
<link rel="author" title="Mozilla" href="https://mozilla.org">
<link rel="match" href="layer-stylesheet-sharing-ref.html">
<style>
  target {
    display: block;
    width: 100px;
    height: 100px;
  }
</style>
<link rel=stylesheet href="data:text/css,@layer{target{background-color:green}}">
<style>
@layer A { target { background-color: red } }
</style>
<link rel=stylesheet href="data:text/css,@layer{target{background-color:green}}">
<target></target>