Choose 16:9 and the band gets shorter than the picture — the ratio becomes a slot
shape and the site serves a rendition cut to it, rather than a whole photograph
scaled down by the browser.
`setContent` writes the whole content object, because the API replaces it rather
than merging: a PATCH with `{ ratio }` alone would drop the url.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>