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                <h1 id="h1">Does This Browser Support @layer?</h1>
  In <strong>Firefox Nightly</strong>,
  go to <code>about:config</code>
  and toggle the
  feature flag.

  In <strong>Chrome Canary</strong>,
  this currently requires a <a href="">run-time flag</a>
  while opening the browser from the command line.

  To get a more extensive overview of support in your current browser,
  see the Web Platform Tests for
  <a href="">basic <code>@layer</code> support</a>,
  <a href="">layering with <code>@import</code></a>,
  <a href="">layering <code>@keyframes</code></a>.


                /* layers override unlayered styles */
@layer default {
  h1 {
    color: green;

  h1::before {
    content: "✅ ";

/* for readability */
html {
  font-size: clamp(1em, 1em + 0.5vw, 2em);

body {
  margin: 0 auto;
  padding: 1em;
  max-width: 75ch;