fix: Visual differences between live editor and rendered exported HTML

[matthewlipski]

Summary

This PR fixes some visual & DOM inconsistencies between the rendered HTML from a live editor, and the rendered static HTML from exporting blocks.

These differences come mostly from plugins/extensions that use decorations not running when doing an export, as well as a few other fixes due to the HTML being static.

Rationale

One of the use cases of BlockNote is writing content in the editor, taking advantage of its UX and formatting, then exporting that content to HTML so it can be displayed read-only without requiring an editor instance.

However, this is only useful if the static HTML output closely matches what a user sees when editing content in BlockNote.

Changes

• Fixed alignment issue with check list items.
• Added transforms to createInternalHTMLSerializer. These are functions which modify the HTML element created from exporting blocks. See internalHTMLSerializer.ts for more info.
• Added example for comparing a live editor to its exported & rendered static HTML.

Impact

N/A

Testing

TODO (e2e)

Screenshots/Video

N/A

Checklist

• Code follows the project's coding standards.
• Unit tests covering the new feature have been added.
• All existing tests pass.
• The documentation has been updated to reflect the new feature

Additional Notes

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Project	Deployment	Review	Updated (UTC)
blocknote	Ready	Preview	Jan 13, 2026 8:03pm
blocknote-website	Ready	Preview	Jan 13, 2026 8:03pm