a11y: margin citations have `role="listitem"` with no `role="list"` parent

src/format/html/format-html-bootstrap.ts から始め、特に referenceMarginProcessor と div#refs を削除するコードを確認します。提供された reprex を quarto render reprex.qmd でレンダリングし、生成された HTML と axe レポートを調べ、移動された引用が有効な ARIA リストセマンティクスを持ち、aria-required-parent 違反がないことを確認します。

I have:

• searched the issue tracker for similar issues
• installed the latest version of Quarto CLI
• formatted my issue following the Bug Reports guide

Bug description

With citation-location: margin, HTML output contains bibliography entries with role="listitem" but no role="list" ancestor. ARIA requires that listitem is contained by a list parent. axe-core reports this as aria-required-parent (critical impact, WCAG 2.0 A, SC 1.3.1 Info and Relationships).

The cause is in the margin relocation, not in the bibliography markup:

• Pandoc's citeproc emits valid markup: <div id="refs" class="csl-bib-body" role="list"> wraps each <div class="csl-entry" role="listitem">.
• referenceMarginProcessor copies each csl-entry into a new plain <div class="no-row-height column-margin column-container"> next to its citation.
• Quarto then removes div#refs, so no role="list" element remains in the page.

Effect on assistive technology. The margin placement is CSS-only, so in DOM order the relocated entry directly follows the sentence that contains the citation. A screen reader reads the entry at that point, so the content is reachable. But the orphaned role="listitem" makes the announcement unpredictable: screen readers differ on whether to announce a list item, and there is no list context to announce. The citation link (role="doc-biblioref") points to a plain <div> that is not focusable, so the link does not move keyboard focus. This describes the rendered markup — we did not test specific screen readers.

Until this is fixed, the accessible choice is to not set citation-location: margin. The default (citation-location: document) keeps the bibliography as a valid role="list".

The problem is visible on quarto.org: an axe-core 4.10 scan flags #ref-xie2018 on Article Layout.

Note: an AI assistant helped investigate this issue, grounded in a local clone of quarto-cli (per CONTRIBUTING.md, "Using AI tools to investigate").

Steps to reproduce

Render this document with quarto render reprex.qmd:

---
title: "Margin citation reprex"
format:
  html:
    axe:
      output: document
bibliography: refs.bib
citation-location: margin
---

See @xie2018.

with this refs.bib:

@book{xie2018,
  title = {R Markdown: The Definitive Guide},
  author = {Xie, Yihui and Allaire, J.J. and Grolemund, Garrett},
  year = {2018},
  publisher = {Chapman and Hall/CRC}
}

Then open reprex.html in a browser. The axe check appends its report to the end of the document.

Actual behavior

The axe report shows one violation:

Critical · WCAG 2.0 A (1.3.1): Ensure elements with an ARIA role that require parent roles are contained by them

Certain ARIA roles must be contained by particular parents

#ref-xie2018

The flagged element and its container in the rendered HTML:

<div class="no-row-height column-margin column-container"><div id="ref-xie2018" class="csl-entry" role="listitem">
Xie, Yihui, J. J. Allaire, and Garrett Grolemund. 2018. <em>R Markdown: The Definitive Guide</em>. Chapman; Hall/CRC.
</div></div>

The page contains one role="listitem" and zero role="list".

Expected behavior

The relocated bibliography entry has valid ARIA list semantics. Either the margin container carries role="list", or the entry does not carry role="listitem". The axe check reports no violation.

Your environment

• IDE: Positron 2026.08.0 build 213 (rendered with Quarto CLI in the terminal)
• OS: macOS 26.5.2 (build 25F84)

Quarto check output

Quarto 1.10.18

[✓] Checking environment information...
      Quarto cache location: /Users/charlottewickham/Library/Caches/quarto

[✓] Checking versions of quarto binary dependencies...
      Pandoc version 3.10.0: OK
      Dart Sass version 1.101.0: OK
      Deno version 2.7.14: OK
      Typst version 0.15.1: OK

[✓] Checking versions of quarto dependencies......OK

[✓] Checking Quarto installation......OK
      Version: 1.10.18
      Path: /Applications/quarto/bin


[✓] Checking tools....................OK
      TinyTeX: v2026.04
      Chrome Headless Shell: 150.0.7871.115
      VeraPDF: 1.28.2


[✓] Checking LaTeX....................OK
      Using: TinyTex
      Path: /Users/charlottewickham/Library/TinyTeX/bin/universal-darwin
      Version: 2026


[✓] Checking Chrome Headless....................OK
      Using: Chrome Headless Shell installed by Quarto
      Path: /Users/charlottewickham/Library/Application Support/quarto/chrome-headless-shell/chrome-headless-shell-mac-arm64/chrome-headless-shell
      Version: 150.0.7871.115


[✓] Checking basic markdown render....OK


[✓] Checking R installation...........OK
      Version: 4.6.0
      Path: /Library/Frameworks/R.framework/Versions/4.6/Resources
      LibPaths:
        - /Users/charlottewickham/Documents/posit/quarto-web-accessibility-checking-ideas/renv/library/macos/R-4.6/aarch64-apple-darwin23
        - /Users/charlottewickham/Library/Caches/org.R-project.R/R/renv/sandbox/macos/R-4.6/aarch64-apple-darwin23/46003b10
      knitr: 1.51
      rmarkdown: 2.31


[✓] Checking Knitr engine render......OK


[✓] Checking Python 3 installation....OK
      Version: 3.12.2
      Path: /Users/charlottewickham/.pyenv/versions/3.12.2/bin/python3
      Jupyter: 5.9.1
      Kernels: python3


[✓] Checking Jupyter engine render....OK


[✓] Checking Julia installation...