What this is for
- Email snippets: check inline-styled HTML renders correctly before sending through your ESP.
- Component tests: a button, card or layout — tweak and re-render without a full dev server.
- Learning: write markup and see the result side by side; the
<script>tag runs in the preview iframe.
Sandbox notes
- The preview runs in a sandboxed iframe with scripts allowed but no parent access — your code can't touch this page or your data.
- External resources (fonts, CDN links) load normally; if the network blocks them, the preview still renders local markup.
- Forms inside the preview won't submit anywhere (sandbox blocks navigation) — that's a feature for testing.
For full-page previews with responsive widths, resize your browser window — the iframe scales with it. Pair with the Markdown Editor when you're drafting content rather than markup.