pomber/index.html

## index.html
<!DOCTYPE html>
<html lang="en">

<body>
  <template id="my-element-template">
    <p>My <b>custom element</b> markup!</p>
  </template>

  <my-element></my-element>
  <my-element></my-element>

  <script>
    var MyElementProto = Object.create(HTMLElement.prototype);
    MyElementProto.createdCallback = function() {
      var t = document.querySelector('#my-element-template');
      var clone = document.importNode(t.content, true);
      this.appendChild(clone);
    };
    var MyElement = document.registerElement(
      'my-element', { prototype: MyElementProto }
    );
  </script>

</body>

</html>
	<!DOCTYPE html>
	<html lang="en">

	<body>
	<template id="my-element-template">
	<p>My <b>custom element</b> markup!</p>
	</template>

	<my-element></my-element>
	<my-element></my-element>

	<script>
	var MyElementProto = Object.create(HTMLElement.prototype);
	MyElementProto.createdCallback = function() {
	var t = document.querySelector('#my-element-template');
	var clone = document.importNode(t.content, true);
	this.appendChild(clone);
	};
	var MyElement = document.registerElement(
	'my-element', { prototype: MyElementProto }
	);
	</script>

	</body>

	</html>