If we’re following this route (= creating a web-component-like widget), we should really avoid using ID attributes. Could we expose the `<section>` container as a `Toaster.element` getter instead?

If you think we need to keep a way to access the `<p>` element from JS, maybe we could expose the `<section>` and `<p>` elements as `Toaster.containerElement` and `Toaster.messageElement`? (or any better names)