Radio buttons not visible on Linux

[Emiliano Heyns]

Is there anything special I have to do for radio buttons on Linux? One user reports they do not show properly https://github.com/retorquere/zotero-better-bibtex/issues/3403. The UI is fairly simple:

?xml version="1.0"?>
<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
<?xml-stylesheet href="chrome://zotero-platform/content/zotero.css"?>
<?xml-stylesheet href="chrome://global/skin/global.css"?>
<?xml-stylesheet href="chrome://zotero/skin/zotero.css"?>
<?xml-stylesheet href="chrome://zotero-platform/content/overlay.css"?>
<?xml-stylesheet href="chrome://zotero-better-bibtex/content/skin/preferences.css"?>
<?xml-stylesheet href="chrome://zotero-better-bibtex/content/skin/error-report.css" type="text/css"?>
...
      <html:label>
        <html:input type="radio" name="migrate" value="all" onchange="migrate(this)"></html:input> Migrate all Better BibTeX citation keys to Zotero citation keys
      </html:label>
      <html:label id="pinned">
        <html:input type="radio" name="migrate" value="pinned" onchange="migrate(this)"></html:input> Migrate only pinned Better BibTeX citation keys, to Zotero citation keys, and discard the dynamic (non-pinned) Better BibTeX citation keys
      </html:label>
      <html:label>
        <html:input type="radio" name="migrate" value="none" onchange="migrate(this)"></html:input> Discard all Better BibTeX citation keys
      </html:label>