[LeonidasZhak]

Summary

Fix duplicated list text in Quarto output for fmt_markdown() cells.

Thanks to maintainers

Thanks to the gt maintainers for triaging this issue and maintaining Quarto support.

Issue or motivation

Closes #2140. A list-only Markdown cell still duplicates its items in newer Quarto, despite the earlier fix for a similar case in #1957.

Root cause

The base64 wrapper added for #1957 in #1958 handles Quarto's text escaping, but its inline <span> containers remain around block Markdown. Newer Quarto treats the list content as inline text while retaining the list markup, which duplicates the item text.

Change

Use block-level <div> containers when the rendered Markdown contains block elements, while preserving <span> containers for inline-only content. Add regression coverage for both cases and a NEWS entry.

Tests

• devtools::test(filter = "fmt_markdown"): 22 passed.
• Quarto 1.9.38 reproduction: each list item appears once in the rendered table.
• R CMD build --no-manual --compact-vignettes=gs+qpdf: passed.
• R CMD check --as-cran --no-manual: passed with one NOTE for the development version.
• Local covr::package_coverage() and Cobertura export: passed, 75.46% coverage.
• pkgdown::build_site_github_pages(new_process = FALSE, install = FALSE): passed; reported existing missing alt-text notices.

Scope

Changes only the Quarto HTML wrapper selected for block versus inline Markdown, with regression coverage for fmt_markdown() and a NEWS entry. It leaves inline-only markup, non-Quarto rendering, and other output formats unchanged.

• I understand and agree to the Code of Conduct.
• I have listed the change in NEWS.
• I have added testthat coverage.