Styles should not assume the rvt-sticker will be defined

[basham]

The CSS selector rvt-sticker:not(:defined)::before assumes that the Rivet Sticker Element will be defined. However, there may be a case in which the user wants to use a sticker but have it statically rendered by manually copying the sticker SVG code (due to server-side rendering or restrictive front-end environments).

<rvt-sticker>
  <svg…>
</rvt-sticker>

Instead, by updating that selector to rvt-sticker:empty::before, it means that the initial loading style (empty circle background in a pseudo element) will only be applied if the element is empty (such as waiting for the custom element to be defined) — not when there is something there (such as when SVG is manually included or when the custom element is attached to the DOM).

[levimcg]

Nice catch on this!