github-monaco-fix

==> manifest.json <==
{
  "name": "GitHub Tweaks",
  "version": "0.1",
  "description": "Style tweaks for github pages",
  "content_scripts": [
    {
      "matches": ["https://github.com/*", "https://gist.github.com/*"],
      "css": ["tweaks.css"]
    }
  ]
}

==> tweaks.css <==
#files .file .line-data,
#files .file .line-number,
#files .file .data td.line_numbers,
#files .file .data pre,
#files .meta .bubble {
  font-family: Monaco !important;
}