Select text and click a button. Markdown is rendered to HTML on the backend. Raw HTML tags are not rendered — they show up as plain text.
A calculator is written into the text as [calc:key] on its own line — that’s where readers will see it. Place it anywhere, as many times as you like.
An image is uploaded and converted to WebP in two sizes; it goes into the text as  — rewrite the alt text, both screen readers and image search read it. A table needs the dashed row under the header, otherwise it stays a paragraph.
Live data is written as [stats] on its own line and pulls numbers from the article category. It is the one part of the text nobody can copy — it belongs near the top rather than at the end.