<div id=host></div>
<script>
const shadow = host.attachShadow({ mode: 'open'});
shadow.innerHTML = `
<style>
p {
  background-color: antiquewhite;
  padding: 8px;
  border: 1px solid coral;
}

p::first-letter {
  color: blue;
}

p::first-line {
  font-weight: bold;
}
</style>
<p>I should start with a blue I and have a bold first line.</p>
`;
</script>