How do I get the elementRoot of a ChatMessage?

Hooks.on('renderChatMessage, (message, html) => {
    message._svelteComponent = new SurgeRoll(
      {
        target: html[0],
        props: {
          surgeMessage,
          messageId: message._id
        }
      }
    )
}

<script>
  import * as ChatComponents from "~/view/chatmessage/rollchat";
  export let surgeMessage;
</script>

<svelte:component this={ChatComponents[surgeMessage.chatTemplate]} {...$$props} />

elementRoot.style.setProperty("--sheet-color", owner.color);