<!DOCTYPE html>
<title>fieldset and shadow DOM</title>
<link rel=fieldset-foo-ref.html>
<p>There should be a normal fieldset below with the legend "Foo".</p>
<template id="my-fieldset">
  <fieldset><slot name="my-text"></slot></fieldset>
</template>

<my-fieldset>
  <legend slot="my-text">Foo</legend>
</my-fieldset>

<script>
customElements.define('my-fieldset',
  class extends HTMLElement {
    constructor() {
      super();

      const template = document.getElementById('my-fieldset');
      const templateContent = template.content;

      this.attachShadow({mode: 'open'}).appendChild(
        templateContent.cloneNode(true)
      );
    }
  }
);
</script>