Quick summary

When we use the HTML code for the accordion recommended in our docs there isn't any arrow. Seems this element is not printed in HTML:
[screen recording redacted]

Steps to reproduce

1. Activate Apostrophe 2 theme
2. Create HTML block
3. Add code for accordion: https://wordpress.com/support/advanced-html/#collapsible-content-accordion-effect

<details>
  <summary>What can you use WordPress.com for?</summary>
    <ul>
     <li>To blog!</li>
     <li>To showcase my professional work.</li>
     <li>To create an online presence for my business.</li>
   </ul>
</details>

What you expected to happen

The arrow is visible in frontend

What actually happened

Arrow is visible only in the editor (block preview)

Impact

Some (< 50%)

Available workarounds?

Yes, easy to implement

Platform (Simple and/or Atomic)

No response

6227396-zd-woothemes

No response